diff --git a/common/error.go b/common/error.go
index 88c9e39..b4b73b1 100644
--- a/common/error.go
+++ b/common/error.go
@@ -3,3 +3,4 @@ package common
 import "fmt"
 
 var ErrEventExpired = fmt.Errorf("event expired")
+var ErrDuplicatedSlashing = fmt.Errorf("duplicated slashing")
diff --git a/verifier/hash_verifier.go b/verifier/hash_verifier.go
index 38ac367..a86e5b8 100644
--- a/verifier/hash_verifier.go
+++ b/verifier/hash_verifier.go
@@ -286,7 +286,8 @@ func (v *Verifier) preCheck(event *model.Event, currentHeight uint64) error {
 			return err
 		}
 		if found {
-			return v.dataProvider.UpdateEventStatus(event.ChallengeId, model.Duplicated)
+			_ = v.dataProvider.UpdateEventStatus(event.ChallengeId, model.Duplicated)
+			return common.ErrDuplicatedSlashing
 		}
 	}