diff --git a/tools/cooja/contiki_tests/rime_runicast.js b/tools/cooja/contiki_tests/rime_runicast.js
index d8a8a9fd9..3221bb5cd 100644
--- a/tools/cooja/contiki_tests/rime_runicast.js
+++ b/tools/cooja/contiki_tests/rime_runicast.js
@@ -7,7 +7,7 @@ nr_sent = 0;
 while (nr_sent < 10) {
 
 /* Count received packets */
-if (msg.contains('received')) {
+if (msg.contains('received') && !msg.contains('DUPLICATE')) {
   nr_recv++;
   log.log("RECV=" + nr_recv + ", sent=" + nr_sent + ", timedout=" + nr_timedout + "\n");
 }