diff --git a/internal/net/grpc/stream.go b/internal/net/grpc/stream.go
index eac59c976c..631d139576 100644
--- a/internal/net/grpc/stream.go
+++ b/internal/net/grpc/stream.go
@@ -22,6 +22,7 @@ import (
 	"context"
 	"fmt"
 	"runtime"
+	"slices"
 	"sync/atomic"
 
 	"github.com/vdaas/vald/internal/errors"
@@ -32,7 +33,6 @@ import (
 	"github.com/vdaas/vald/internal/net/grpc/status"
 	"github.com/vdaas/vald/internal/observability/trace"
 	"github.com/vdaas/vald/internal/safety"
-	"github.com/vdaas/vald/internal/slices"
 	"github.com/vdaas/vald/internal/sync"
 	"github.com/vdaas/vald/internal/sync/errgroup"
 	"google.golang.org/grpc"
@@ -75,7 +75,7 @@ func BidirectionalStream[Q any, R any](ctx context.Context, stream ServerStream,
 			errs = append(errs, err)
 			emu.Unlock()
 		}
-		slices.RemoveDuplicates(errs, func(left, right error) int {
+		removeDuplicates(errs, func(left, right error) int {
 			return cmp.Compare(left.Error(), right.Error())
 		})
 		emu.Lock()
@@ -229,3 +229,11 @@ func BidirectionalStreamClient(stream ClientStream,
 		}
 	}()
 }
+
+func removeDuplicates[E comparable](x []E, less func(left, right E) int) []E {
+	if len(x) < 2 {
+		return x
+	}
+	slices.SortStableFunc(x, less)
+	return slices.Compact(x)
+}
diff --git a/pkg/gateway/lb/handler/grpc/aggregation.go b/pkg/gateway/lb/handler/grpc/aggregation.go
index e29a4a46bc..8a700c8edd 100644
--- a/pkg/gateway/lb/handler/grpc/aggregation.go
+++ b/pkg/gateway/lb/handler/grpc/aggregation.go
@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"math"
 	"math/big"
+	"slices"
 	"sync/atomic"
 	"time"
 
@@ -31,7 +32,6 @@ import (
 	"github.com/vdaas/vald/internal/net/grpc/errdetails"
 	"github.com/vdaas/vald/internal/net/grpc/status"
 	"github.com/vdaas/vald/internal/observability/trace"
-	"github.com/vdaas/vald/internal/slices"
 	"github.com/vdaas/vald/internal/sync"
 )
 
@@ -557,7 +557,7 @@ func newSlice(num, replica int) Aggregator {
 	}
 }
 
-func (_ *valdSliceAggr) Start(_ context.Context) {}
+func (*valdSliceAggr) Start(_ context.Context) {}
 
 func (v *valdSliceAggr) Send(ctx context.Context, data *payload.Search_Response) {
 	result := data.GetResults()
@@ -580,7 +580,7 @@ func (v *valdSliceAggr) Send(ctx context.Context, data *payload.Search_Response)
 }
 
 func (v *valdSliceAggr) Result() (res *payload.Search_Response) {
-	slices.RemoveDuplicates(v.result, func(l, r *DistPayload) int {
+	removeDuplicates(v.result, func(l, r *DistPayload) int {
 		return l.distance.Cmp(r.distance)
 	})
 
@@ -646,7 +646,7 @@ func (v *valdPoolSliceAggr) Send(ctx context.Context, data *payload.Search_Respo
 }
 
 func (v *valdPoolSliceAggr) Result() (res *payload.Search_Response) {
-	slices.RemoveDuplicates(v.result, func(l, r *DistPayload) int {
+	removeDuplicates(v.result, func(l, r *DistPayload) int {
 		return l.distance.Cmp(r.distance)
 	})
 
@@ -662,3 +662,11 @@ func (v *valdPoolSliceAggr) Result() (res *payload.Search_Response) {
 	poolDist.Put(v.result[:0])
 	return res
 }
+
+func removeDuplicates[E comparable](x []E, less func(left, right E) int) []E {
+	if len(x) < 2 {
+		return x
+	}
+	slices.SortStableFunc(x, less)
+	return slices.Compact(x)
+}