diff --git a/beacon-chain/sync/pending_attestations_queue.go b/beacon-chain/sync/pending_attestations_queue.go
index 82b80324a..66d705db6 100644
--- a/beacon-chain/sync/pending_attestations_queue.go
+++ b/beacon-chain/sync/pending_attestations_queue.go
@@ -1,6 +1,7 @@
 package sync
 
 import (
+	"bytes"
 	"context"
 	"encoding/hex"
 	"sync"
@@ -157,7 +158,8 @@ func (s *Service) processAttestations(ctx context.Context, attestations []*ethpb
 
 // This defines how pending attestations is saved in the map. The key is the
 // root of the missing block. The value is the list of pending attestations
-// that voted for that block root.
+// that voted for that block root. The caller of this function is responsible
+// for not sending repeated attestations to the pending queue.
 func (s *Service) savePendingAtt(att *ethpb.SignedAggregateAttestationAndProof) {
 	root := bytesutil.ToBytes32(att.Message.Aggregate.Data.BeaconBlockRoot)
 
@@ -178,17 +180,32 @@ func (s *Service) savePendingAtt(att *ethpb.SignedAggregateAttestationAndProof)
 		s.blkRootToPendingAtts[root] = []*ethpb.SignedAggregateAttestationAndProof{att}
 		return
 	}
-
-	// Skip if the attestation from the same aggregator already exists in the pending queue.
+	// Skip if the attestation from the same aggregator already exists in
+	// the pending queue.
 	for _, a := range s.blkRootToPendingAtts[root] {
-		if a.Message.AggregatorIndex == att.Message.AggregatorIndex {
+		if attsAreEqual(att, a) {
 			return
 		}
 	}
-
 	s.blkRootToPendingAtts[root] = append(s.blkRootToPendingAtts[root], att)
 }
 
+func attsAreEqual(a, b *ethpb.SignedAggregateAttestationAndProof) bool {
+	if a.Signature != nil {
+		return b.Signature != nil && a.Message.AggregatorIndex == b.Message.AggregatorIndex
+	}
+	if b.Signature != nil {
+		return false
+	}
+	if a.Message.Aggregate.Data.Slot != b.Message.Aggregate.Data.Slot {
+		return false
+	}
+	if a.Message.Aggregate.Data.CommitteeIndex != b.Message.Aggregate.Data.CommitteeIndex {
+		return false
+	}
+	return bytes.Equal(a.Message.Aggregate.AggregationBits, b.Message.Aggregate.AggregationBits)
+}
+
 // This validates the pending attestations in the queue are still valid.
 // If not valid, a node will remove it in the queue in place. The validity
 // check specifies the pending attestation could not fall one epoch behind
diff --git a/beacon-chain/sync/pending_attestations_queue_test.go b/beacon-chain/sync/pending_attestations_queue_test.go
index 88288f310..3f32b8fa8 100644
--- a/beacon-chain/sync/pending_attestations_queue_test.go
+++ b/beacon-chain/sync/pending_attestations_queue_test.go
@@ -399,7 +399,7 @@ func TestValidatePendingAtts_CanPruneOldAtts(t *testing.T) {
 	assert.Equal(t, 0, len(s.blkRootToPendingAtts), "Did not delete block keys")
 }
 
-func TestValidatePendingAtts_NoDuplicatingAggregatorIndex(t *testing.T) {
+func TestValidatePendingAtts_NoDuplicatingAtts(t *testing.T) {
 	s := &Service{
 		blkRootToPendingAtts: make(map[[32]byte][]*ethpb.SignedAggregateAttestationAndProof),
 	}
@@ -420,7 +420,7 @@ func TestValidatePendingAtts_NoDuplicatingAggregatorIndex(t *testing.T) {
 		Message: &ethpb.AggregateAttestationAndProof{
 			AggregatorIndex: 2,
 			Aggregate: &ethpb.Attestation{
-				Data: &ethpb.AttestationData{Slot: 3, BeaconBlockRoot: r2[:]}}}})
+				Data: &ethpb.AttestationData{Slot: 2, BeaconBlockRoot: r2[:]}}}})
 
 	assert.Equal(t, 1, len(s.blkRootToPendingAtts[r1]), "Did not save pending atts")
 	assert.Equal(t, 1, len(s.blkRootToPendingAtts[r2]), "Did not save pending atts")