diff --git a/test/edu/nps/moves/dis7/SignalPdusTest.java b/test/edu/nps/moves/dis7/SignalPdusTest.java
index 0c62da965218f7f7d3820bbbc04d3c546a041ea1..aa97bd22680fba5041142dac5acb7d8a487f8b98 100644
--- a/test/edu/nps/moves/dis7/SignalPdusTest.java
+++ b/test/edu/nps/moves/dis7/SignalPdusTest.java
@@ -156,7 +156,8 @@ public class SignalPdusTest {
     }
 
     private static void handleReceivedPdu(Pdu pdu) {
-        receivedPdus.add(pdu);
+        if (!receivedPdus.contains(pdu))
+            receivedPdus.add(pdu);
     }
 
     public static void main(String[] args) throws IOException, InterruptedException {