diff --git a/shared/bytesutil/bytes.go b/shared/bytesutil/bytes.go
index 0c3e1df8816e..abdab6d970f6 100644
--- a/shared/bytesutil/bytes.go
+++ b/shared/bytesutil/bytes.go
@@ -133,6 +133,15 @@ func ToBytes48(x []byte) [48]byte {
 	return y
 }
 
+// ToBytes64 is a convenience method for converting a byte slice to a fix
+// sized 64 byte array. This method will truncate the input if it is larger
+// than 64 bytes.
+func ToBytes64(x []byte) [64]byte {
+	var y [64]byte
+	copy(y[:], x)
+	return y
+}
+
 // ToBool is a convenience method for converting a byte to a bool.
 // This method will use the first bit of the 0 byte to generate the returned value.
 func ToBool(x byte) bool {
diff --git a/validator/client/validator.go b/validator/client/validator.go
index 3cc9261d2422..421a1274fed4 100644
--- a/validator/client/validator.go
+++ b/validator/client/validator.go
@@ -292,6 +292,7 @@ func (v *validator) UpdateDuties(ctx context.Context, slot uint64) error {
 	subscribeSlots := make([]uint64, 0, len(validatingKeys))
 	subscribeCommitteeIDs := make([]uint64, 0, len(validatingKeys))
 	subscribeIsAggregator := make([]bool, 0, len(validatingKeys))
+	alreadySubscribed := make(map[[64]byte]bool)
 	// Only log the full assignments output on epoch start to be less verbose.
 	// Also log out on first launch so the user doesn't have to wait a whole epoch to see their assignments.
 	if slot%params.BeaconConfig().SlotsPerEpoch == 0 || firstDutiesReceived {
@@ -310,17 +311,28 @@ func (v *validator) UpdateDuties(ctx context.Context, slot uint64) error {
 			}
 
 			if duty.Status == ethpb.ValidatorStatus_ACTIVE {
+				attesterSlot := duty.AttesterSlot
+				committeeIndex := duty.CommitteeIndex
+
 				if duty.ProposerSlot > 0 {
 					lFields["proposerSlot"] = duty.ProposerSlot
 				}
-				lFields["attesterSlot"] = duty.AttesterSlot
+				lFields["attesterSlot"] = attesterSlot
+
+				alreadySubscribedKey := validatorSubscribeKey(attesterSlot, committeeIndex)
+				if _, ok := alreadySubscribed[alreadySubscribedKey]; ok {
+					continue
+				}
 
-				aggregator, err := v.isAggregator(ctx, duty.Committee, duty.AttesterSlot, bytesutil.ToBytes48(duty.PublicKey))
+				aggregator, err := v.isAggregator(ctx, duty.Committee, attesterSlot, bytesutil.ToBytes48(duty.PublicKey))
 				if err != nil {
 					return errors.Wrap(err, "could not check if a validator is an aggregator")
 				}
-				subscribeSlots = append(subscribeSlots, duty.AttesterSlot)
-				subscribeCommitteeIDs = append(subscribeCommitteeIDs, duty.CommitteeIndex)
+				if aggregator {
+					alreadySubscribed[alreadySubscribedKey] = true
+				}
+				subscribeSlots = append(subscribeSlots, attesterSlot)
+				subscribeCommitteeIDs = append(subscribeCommitteeIDs, committeeIndex)
 				subscribeIsAggregator = append(subscribeIsAggregator, aggregator)
 			}
 
@@ -338,12 +350,24 @@ func (v *validator) UpdateDuties(ctx context.Context, slot uint64) error {
 	if slot%params.BeaconConfig().SlotsPerEpoch == 0 || firstDutiesReceived {
 		for _, duty := range dutiesNextEpoch.Duties {
 			if duty.Status == ethpb.ValidatorStatus_ACTIVE {
-				aggregator, err := v.isAggregator(ctx, duty.Committee, duty.AttesterSlot, bytesutil.ToBytes48(duty.PublicKey))
+				attesterSlot := duty.AttesterSlot
+				committeeIndex := duty.CommitteeIndex
+
+				alreadySubscribedKey := validatorSubscribeKey(attesterSlot, committeeIndex)
+				if _, ok := alreadySubscribed[alreadySubscribedKey]; ok {
+					continue
+				}
+
+				aggregator, err := v.isAggregator(ctx, duty.Committee, attesterSlot, bytesutil.ToBytes48(duty.PublicKey))
 				if err != nil {
 					return errors.Wrap(err, "could not check if a validator is an aggregator")
 				}
-				subscribeSlots = append(subscribeSlots, duty.AttesterSlot)
-				subscribeCommitteeIDs = append(subscribeCommitteeIDs, duty.CommitteeIndex)
+				if aggregator {
+					alreadySubscribed[alreadySubscribedKey] = true
+				}
+
+				subscribeSlots = append(subscribeSlots, attesterSlot)
+				subscribeCommitteeIDs = append(subscribeCommitteeIDs, committeeIndex)
 				subscribeIsAggregator = append(subscribeIsAggregator, aggregator)
 			}
 		}
@@ -461,3 +485,9 @@ func (v *validator) domainData(ctx context.Context, epoch uint64, domain []byte)
 
 	return res, nil
 }
+
+// This constructs a validator subscribed key, it's used to track
+// which subnet has already been pending requested.
+func validatorSubscribeKey(slot uint64, committeeID uint64) [64]byte {
+	return bytesutil.ToBytes64(append(bytesutil.Bytes32(slot), bytesutil.Bytes32(committeeID)...))
+}