diff --git a/thehive-backend/app/services/CaseMergeSrv.scala b/thehive-backend/app/services/CaseMergeSrv.scala
index 0164e855af..1da5254a37 100644
--- a/thehive-backend/app/services/CaseMergeSrv.scala
+++ b/thehive-backend/app/services/CaseMergeSrv.scala
@@ -197,7 +197,7 @@ class CaseMergeSrv @Inject() (
           .set("message", concat[Artifact](sameArtifacts, "\n  \n", a ⇒ caseMap(a.parentId.get).caseId(), _.message()))
           .set("startDate", firstDate(sameArtifacts.map(_.startDate())))
           .set("tlp", JsNumber(sameArtifacts.map(_.tlp()).min))
-          .set("tags", JsArray(sameArtifacts.flatMap(_.tags()).map(JsString)))
+          .set("tags", JsArray(sameArtifacts.flatMap(_.tags()).distinct.map(JsString)))
           .set("ioc", JsBoolean(sameArtifacts.map(_.ioc()).reduce(_ || _)))
           .set("status", mergeArtifactStatus(sameArtifacts))
         // Merged artifact is created under new case