diff --git a/src/Stream/Configuration.php b/src/Stream/Configuration.php
index 554f98d..75102d4 100644
--- a/src/Stream/Configuration.php
+++ b/src/Stream/Configuration.php
@@ -20,6 +20,7 @@ class Configuration
     private string $retentionPolicy = RetentionPolicy::LIMITS;
     private string $storageBackend = StorageBackend::FILE;
 
+    private ?float $duplicateWindow = null;
     private ?int $maxBytes = null;
     private ?int $maxMessageSize = null;
     private ?int $maxMessagesPerSubject = null;
@@ -61,6 +62,11 @@ public function getDiscardPolicy(): string
         return $this->discardPolicy;
     }
 
+    public function getDuplicateWindow(): ?float
+    {
+        return $this->duplicateWindow;
+    }
+
     public function getMaxAge(): ?int
     {
         return $this->maxAge;
@@ -129,6 +135,12 @@ public function setDiscardPolicy(string $policy): self
         return $this;
     }
 
+    public function setDuplicateWindow(?float $seconds): self
+    {
+        $this->duplicateWindow = $seconds;
+        return $this;
+    }
+
     public function setMaxAge(?int $maxAge): self
     {
         $this->maxAge = $maxAge;
@@ -190,6 +202,7 @@ public function toArray(): array
             'deny_delete' => $this->getDenyDelete(),
             'description' => $this->getDescription(),
             'discard' => $this->getDiscardPolicy(),
+            'duplicate_window' => $this->getDuplicateWindow() * 1_000_000_000,
             'max_age' => $this->getMaxAge(),
             'max_bytes' => $this->getMaxBytes(),
             'max_consumers' => $this->getMaxConsumers(),
diff --git a/tests/StreamTest.php b/tests/StreamTest.php
index 5a0724b..1a74c02 100644
--- a/tests/StreamTest.php
+++ b/tests/StreamTest.php
@@ -15,9 +15,19 @@ class StreamTest extends Test
     public function testDeduplication()
     {
         $stream = $this->getClient()->getApi()->getStream('tester');
-        $stream->getConfiguration()->setSubjects(['tester']);
+        $stream->getConfiguration()
+            ->setSubjects(['tester'])
+            ->setDuplicateWindow(0.5); // 500ms windows duplicate
+
         $stream->create();
 
+        // windows value using nanoseconds
+        $this->assertEquals(0.5 * 1_000_000_000, $stream->info()->getValue('config.duplicate_window'));
+
+        $stream->put('tester', new Payload("hello", [
+            'Nats-Msg-Id' => 'the-message'
+        ]));
+
         $stream->put('tester', new Payload("hello", [
             'Nats-Msg-Id' => 'the-message'
         ]));
@@ -39,6 +49,21 @@ public function testDeduplication()
             'Nats-Msg-Id' => 'the-message'
         ]));
         $this->assertSame(0, $consumer->info()->num_pending);
+
+        // 500ms sleep
+        usleep(500 * 1_000);
+
+        $stream->put('tester', new Payload("hello", [
+            'Nats-Msg-Id' => 'the-message'
+        ]));
+        $this->assertSame(1, $consumer->info()->num_pending);
+
+        usleep(500 * 1_000);
+
+        $stream->put('tester', new Payload("hello", [
+            'Nats-Msg-Id' => 'the-message'
+        ]));
+        $this->assertSame(2, $consumer->info()->num_pending);
     }
 
     public function testInterrupt()