diff --git a/pkg/store/bucket_test.go b/pkg/store/bucket_test.go
index 54dd9a09e4..8d75ed6b04 100644
--- a/pkg/store/bucket_test.go
+++ b/pkg/store/bucket_test.go
@@ -34,6 +34,7 @@ import (
 	promtest "github.com/prometheus/client_golang/prometheus/testutil"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/model/relabel"
+	"github.com/prometheus/prometheus/model/timestamp"
 	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/tsdb"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
@@ -3341,3 +3342,99 @@ func TestBucketIndexReader_decodeCachedPostingsErrors(t *testing.T) {
 		testutil.NotOk(t, err)
 	})
 }
+
+func TestBucketStoreDedupOnBlockSeriesSet(t *testing.T) {
+	t.Skip("Known Issue, Added for debugging in followup PR.")
+
+	logger := log.NewNopLogger()
+	tmpDir := t.TempDir()
+	bktDir := filepath.Join(tmpDir, "bkt")
+	auxDir := filepath.Join(tmpDir, "aux")
+	metaDir := filepath.Join(tmpDir, "meta")
+	extLset := labels.FromStrings("region", "eu-west")
+
+	testutil.Ok(t, os.MkdirAll(metaDir, os.ModePerm))
+	testutil.Ok(t, os.MkdirAll(auxDir, os.ModePerm))
+
+	bkt, err := filesystem.NewBucket(bktDir)
+	testutil.Ok(t, err)
+	t.Cleanup(func() { testutil.Ok(t, bkt.Close()) })
+
+	for i := 0; i < 2; i++ {
+		headOpts := tsdb.DefaultHeadOptions()
+		headOpts.ChunkDirRoot = tmpDir
+		headOpts.ChunkRange = 1000
+		h, err := tsdb.NewHead(nil, nil, nil, nil, headOpts, nil)
+		testutil.Ok(t, err)
+		t.Cleanup(func() { testutil.Ok(t, h.Close()) })
+
+		app := h.Appender(context.Background())
+		_, err = app.Append(0, labels.FromStrings("replica", "a", "z", "1"), 0, 1)
+		testutil.Ok(t, err)
+		_, err = app.Append(0, labels.FromStrings("replica", "a", "z", "2"), 0, 1)
+		testutil.Ok(t, err)
+		_, err = app.Append(0, labels.FromStrings("replica", "b", "z", "1"), 0, 1)
+		testutil.Ok(t, err)
+		_, err = app.Append(0, labels.FromStrings("replica", "b", "z", "2"), 0, 1)
+		testutil.Ok(t, err)
+		testutil.Ok(t, app.Commit())
+
+		id := createBlockFromHead(t, auxDir, h)
+
+		auxBlockDir := filepath.Join(auxDir, id.String())
+		_, err = metadata.InjectThanos(log.NewNopLogger(), auxBlockDir, metadata.Thanos{
+			Labels:     extLset.Map(),
+			Downsample: metadata.ThanosDownsample{Resolution: 0},
+			Source:     metadata.TestSource,
+		}, nil)
+		testutil.Ok(t, err)
+
+		testutil.Ok(t, block.Upload(context.Background(), logger, bkt, auxBlockDir, metadata.NoneFunc))
+		testutil.Ok(t, block.Upload(context.Background(), logger, bkt, auxBlockDir, metadata.NoneFunc))
+	}
+
+	chunkPool, err := NewDefaultChunkBytesPool(2e5)
+	testutil.Ok(t, err)
+
+	metaFetcher, err := block.NewMetaFetcher(logger, 20, objstore.WithNoopInstr(bkt), metaDir, nil, []block.MetadataFilter{
+		block.NewTimePartitionMetaFilter(allowAllFilterConf.MinTime, allowAllFilterConf.MaxTime),
+	})
+	testutil.Ok(t, err)
+
+	bucketStore, err := NewBucketStore(
+		objstore.WithNoopInstr(bkt),
+		metaFetcher,
+		"",
+		NewChunksLimiterFactory(10e6),
+		NewSeriesLimiterFactory(10e6),
+		NewBytesLimiterFactory(10e6),
+		NewGapBasedPartitioner(PartitionerMaxGapSize),
+		20,
+		true,
+		DefaultPostingOffsetInMemorySampling,
+		false,
+		false,
+		1*time.Minute,
+		WithChunkPool(chunkPool),
+		WithFilterConfig(allowAllFilterConf),
+	)
+	testutil.Ok(t, err)
+	t.Cleanup(func() { testutil.Ok(t, bucketStore.Close()) })
+
+	testutil.Ok(t, bucketStore.SyncBlocks(context.Background()))
+
+	// make sure to have updated inner label names
+	bucketStore.UpdateLabelNames()
+
+	srv := newStoreSeriesServer(context.Background())
+	testutil.Ok(t, bucketStore.Series(&storepb.SeriesRequest{
+		WithoutReplicaLabels: []string{"replica"},
+		MinTime:              timestamp.FromTime(minTime),
+		MaxTime:              timestamp.FromTime(maxTime),
+		Matchers: []storepb.LabelMatcher{
+			{Type: storepb.LabelMatcher_NEQ, Name: "z", Value: ""},
+		},
+	}, srv))
+
+	testutil.Equals(t, 2, len(srv.SeriesSet))
+}