diff --git a/src/Analyser/ProjectZomboid/ItemDuplicationAnalyser.php b/src/Analyser/ProjectZomboid/ItemDuplicationAnalyser.php
new file mode 100644
index 0000000..f525703
--- /dev/null
+++ b/src/Analyser/ProjectZomboid/ItemDuplicationAnalyser.php
@@ -0,0 +1,90 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Analyser\ProjectZomboid;
+
+use IndifferentKetchup\Codex\Analyser\Analyser;
+use IndifferentKetchup\Codex\Analysis\Analysis;
+use IndifferentKetchup\Codex\Analysis\AnalysisInterface;
+use IndifferentKetchup\Codex\Analysis\ProjectZomboid\ItemDuplicationProblem;
+use IndifferentKetchup\Codex\Pattern\ProjectZomboid\ItemPattern;
+
+/**
+ * Flags suspicious item-gain frequency per (player, item) tuple. Slides a
+ * fixed-second window across each group's events; a window with at least
+ * THRESHOLD_COUNT positive-delta events triggers a problem.
+ *
+ * Negative-delta events (drops, transfers out) are ignored — they do not
+ * indicate creation of items and a sufficiently fast trade-and-pickup loop
+ * would self-cancel.
+ *
+ * Entry::getTime() resolves to integer Unix seconds, so sub-second
+ * timestamps in the fixture all collapse to the same value. This is
+ * acceptable for v1: events emitted within the same second are by
+ * definition within any positive window.
+ */
+class ItemDuplicationAnalyser extends Analyser
+{
+    /**
+     * Minimum number of same-item gain events that must fall inside the
+     * window before a Problem is emitted. Five was picked because legitimate
+     * gameplay rarely produces five identical items in ten seconds:
+     * crafting has animation delays, looting is one-at-a-time, and zombie
+     * drops are similarly serial. A burst of five suggests admin-spawn or
+     * exploit. Tune downward if false negatives appear in production logs.
+     */
+    public const int THRESHOLD_COUNT = 5;
+
+    /**
+     * Length of the sliding window in seconds. Ten seconds covers a
+     * realistic burst-loot scenario (e.g. crate of identical items) without
+     * collapsing onto unrelated events. Combined with THRESHOLD_COUNT this
+     * means an effective rate of 0.5 same-item events per second.
+     */
+    public const int THRESHOLD_WINDOW_SECONDS = 10;
+
+    public function analyse(): AnalysisInterface
+    {
+        $analysis = new Analysis();
+        $analysis->setLog($this->log);
+
+        $groups = [];
+        foreach ($this->log as $entry) {
+            if (preg_match(ItemPattern::FIELDS, (string) $entry, $m) !== 1) {
+                continue;
+            }
+            if (!str_starts_with($m['delta'], '+')) {
+                continue;
+            }
+            $key = $m['steamid'] . '|' . $m['item'];
+            $groups[$key][] = [
+                'time' => $entry->getTime() ?? 0,
+                'steamid' => $m['steamid'],
+                'item' => $m['item'],
+                'player' => $m['player'],
+            ];
+        }
+
+        foreach ($groups as $events) {
+            usort($events, static fn($a, $b) => $a['time'] <=> $b['time']);
+
+            $left = 0;
+            $eventCount = count($events);
+            for ($right = 0; $right < $eventCount; $right++) {
+                while ($events[$right]['time'] - $events[$left]['time'] > self::THRESHOLD_WINDOW_SECONDS) {
+                    $left++;
+                }
+                if (($right - $left + 1) >= self::THRESHOLD_COUNT) {
+                    $sample = $events[0];
+                    $analysis->addInsight((new ItemDuplicationProblem())
+                        ->setSteamId($sample['steamid'])
+                        ->setPlayer($sample['player'])
+                        ->setItem($sample['item'])
+                        ->setEventCount($eventCount));
+                    break;
+                }
+            }
+        }
+
+        return $analysis;
+    }
+}
diff --git a/src/Analysis/ProjectZomboid/ItemDuplicationProblem.php b/src/Analysis/ProjectZomboid/ItemDuplicationProblem.php
new file mode 100644
index 0000000..7f5c414
--- /dev/null
+++ b/src/Analysis/ProjectZomboid/ItemDuplicationProblem.php
@@ -0,0 +1,82 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Analysis\ProjectZomboid;
+
+use IndifferentKetchup\Codex\Analysis\InsightInterface;
+use IndifferentKetchup\Codex\Analysis\Problem;
+
+/**
+ * Problem emitted by ItemDuplicationAnalyser when a player gains the same
+ * item code at a rate that exceeds the configured threshold. Coalesced by
+ * the (Steam ID, item code) tuple so each suspicious group produces one
+ * problem regardless of how many events fall inside the window.
+ */
+class ItemDuplicationProblem extends Problem
+{
+    private string $steamId = '';
+    private string $player = '';
+    private string $item = '';
+    private int $eventCount = 0;
+
+    public function setSteamId(string $steamId): static
+    {
+        $this->steamId = $steamId;
+        return $this;
+    }
+
+    public function setPlayer(string $player): static
+    {
+        $this->player = $player;
+        return $this;
+    }
+
+    public function setItem(string $item): static
+    {
+        $this->item = $item;
+        return $this;
+    }
+
+    public function setEventCount(int $count): static
+    {
+        $this->eventCount = $count;
+        return $this;
+    }
+
+    public function getSteamId(): string
+    {
+        return $this->steamId;
+    }
+
+    public function getPlayer(): string
+    {
+        return $this->player;
+    }
+
+    public function getItem(): string
+    {
+        return $this->item;
+    }
+
+    public function getEventCount(): int
+    {
+        return $this->eventCount;
+    }
+
+    public function getMessage(): string
+    {
+        return sprintf(
+            'Player %s (%s) gained %s %d times at a rate above the duplication threshold.',
+            $this->player,
+            $this->steamId,
+            $this->item,
+            $this->eventCount
+        );
+    }
+
+    public function isEqual(InsightInterface $insight): bool
+    {
+        return $insight instanceof self
+            && $insight->getSteamId() === $this->steamId
+            && $insight->getItem() === $this->item;
+    }
+}
diff --git a/src/Log/ProjectZomboid/ProjectZomboidItemLog.php b/src/Log/ProjectZomboid/ProjectZomboidItemLog.php
index d7ebc9c..7a831b0 100644
--- a/src/Log/ProjectZomboid/ProjectZomboidItemLog.php
+++ b/src/Log/ProjectZomboid/ProjectZomboidItemLog.php
@@ -3,7 +3,7 @@
 namespace IndifferentKetchup\Codex\Log\ProjectZomboid;
 
 use IndifferentKetchup\Codex\Analyser\AnalyserInterface;
-use IndifferentKetchup\Codex\Analyser\PatternAnalyser;
+use IndifferentKetchup\Codex\Analyser\ProjectZomboid\ItemDuplicationAnalyser;
 use IndifferentKetchup\Codex\Detective\FilenameDetector;
 use IndifferentKetchup\Codex\Detective\WeightedSinglePatternDetector;
 use IndifferentKetchup\Codex\Parser\ParserInterface;
@@ -22,7 +22,7 @@ class ProjectZomboidItemLog extends ProjectZomboidEventLog
 
     public static function getDefaultAnalyser(): AnalyserInterface
     {
-        return new PatternAnalyser();
+        return new ItemDuplicationAnalyser();
     }
 
     public static function getDetectors(): array
diff --git a/test/src/Games/ProjectZomboid/fixtures/item-minimal.txt b/test/src/Games/ProjectZomboid/fixtures/item-minimal.txt
index 96bbad7..e88ff6c 100644
--- a/test/src/Games/ProjectZomboid/fixtures/item-minimal.txt
+++ b/test/src/Games/ProjectZomboid/fixtures/item-minimal.txt
@@ -8,3 +8,13 @@
 [16-04-26 19:35:42.812] 76561198000000001 "Player1" container -1 1002,2002,0 [Base.WaterBottleFull].
 [16-04-26 19:40:00.514] 76561198000000002 "Player2" floor +1 1011,2011,0 [Base.Bandage].
 [16-04-26 19:42:25.223] 76561198000000002 "Player2" inventory +5 1011,2011,0 [Base.Bullets9mm].
+[16-04-26 19:50:00.001] 76561198000000003 "AdminUser" inventory +1 1020,2020,0 [Base.Bullets9mm].
+[16-04-26 19:50:00.002] 76561198000000003 "AdminUser" inventory +1 1020,2020,0 [Base.Bullets9mm].
+[16-04-26 19:50:00.003] 76561198000000003 "AdminUser" inventory +1 1020,2020,0 [Base.Bullets9mm].
+[16-04-26 19:50:00.004] 76561198000000003 "AdminUser" inventory +1 1020,2020,0 [Base.Bullets9mm].
+[16-04-26 19:50:00.005] 76561198000000003 "AdminUser" inventory +1 1020,2020,0 [Base.Bullets9mm].
+[16-04-26 19:50:00.006] 76561198000000003 "AdminUser" inventory +1 1020,2020,0 [Base.Bullets9mm].
+[16-04-26 20:00:00.000] 76561198000000001 "Player1" floor +1 1004,2004,0 [Base.Plank].
+[16-04-26 20:01:00.000] 76561198000000001 "Player1" floor +1 1004,2004,0 [Base.Plank].
+[16-04-26 20:02:00.000] 76561198000000001 "Player1" floor +1 1004,2004,0 [Base.Plank].
+[16-04-26 20:03:00.000] 76561198000000001 "Player1" floor +1 1004,2004,0 [Base.Plank].
diff --git a/test/tests/Games/ProjectZomboid/Analyser/ItemLogAnalysisTest.php b/test/tests/Games/ProjectZomboid/Analyser/ItemLogAnalysisTest.php
new file mode 100644
index 0000000..95bd079
--- /dev/null
+++ b/test/tests/Games/ProjectZomboid/Analyser/ItemLogAnalysisTest.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Test\Tests\Games\ProjectZomboid\Analyser;
+
+use IndifferentKetchup\Codex\Analyser\ProjectZomboid\ItemDuplicationAnalyser;
+use IndifferentKetchup\Codex\Analysis\ProjectZomboid\ItemDuplicationProblem;
+use IndifferentKetchup\Codex\Log\File\PathLogFile;
+use IndifferentKetchup\Codex\Log\ProjectZomboid\ProjectZomboidItemLog;
+use PHPUnit\Framework\TestCase;
+
+class ItemLogAnalysisTest extends TestCase
+{
+    private function fixturePath(): string
+    {
+        return __DIR__ . '/../../../../src/Games/ProjectZomboid/fixtures/item-minimal.txt';
+    }
+
+    public function testFlagsBurstOfSameItemAboveThreshold(): void
+    {
+        $log = (new ProjectZomboidItemLog())->setLogFile(new PathLogFile($this->fixturePath()));
+        $log->parse();
+        $analysis = $log->analyse();
+
+        $problems = $analysis->getFilteredInsights(ItemDuplicationProblem::class);
+        $this->assertCount(1, $problems);
+
+        $problem = $problems[0];
+        $this->assertSame('76561198000000003', $problem->getSteamId());
+        $this->assertSame('AdminUser', $problem->getPlayer());
+        $this->assertSame('Base.Bullets9mm', $problem->getItem());
+        $this->assertSame(6, $problem->getEventCount());
+    }
+
+    public function testDoesNotFlagSubThresholdGroup(): void
+    {
+        $log = (new ProjectZomboidItemLog())->setLogFile(new PathLogFile($this->fixturePath()));
+        $log->parse();
+        $analysis = $log->analyse();
+
+        $problems = $analysis->getFilteredInsights(ItemDuplicationProblem::class);
+        foreach ($problems as $problem) {
+            $this->assertNotSame('Base.Plank', $problem->getItem());
+        }
+    }
+
+    public function testThresholdConstantsAreDocumentedAndPositive(): void
+    {
+        $this->assertGreaterThan(0, ItemDuplicationAnalyser::THRESHOLD_COUNT);
+        $this->assertGreaterThan(0, ItemDuplicationAnalyser::THRESHOLD_WINDOW_SECONDS);
+    }
+}
diff --git a/test/tests/Games/ProjectZomboid/Log/ProjectZomboidItemLogTest.php b/test/tests/Games/ProjectZomboid/Log/ProjectZomboidItemLogTest.php
index 79062b7..3a3cba2 100644
--- a/test/tests/Games/ProjectZomboid/Log/ProjectZomboidItemLogTest.php
+++ b/test/tests/Games/ProjectZomboid/Log/ProjectZomboidItemLogTest.php
@@ -20,7 +20,7 @@ class ProjectZomboidItemLogTest extends TestCase
         $log = (new ProjectZomboidItemLog())->setLogFile(new PathLogFile($this->fixturePath()));
         $log->parse();
 
-        $this->assertCount(10, $log->getEntries());
+        $this->assertCount(20, $log->getEntries());
     }
 
     public function testFieldsRegexExtractsItemAndDelta(): void