diff --git a/index/keyset_test.go b/index/keyset_test.go
index 3dd43d4..67a382b 100644
--- a/index/keyset_test.go
+++ b/index/keyset_test.go
@@ -35,3 +35,16 @@ func TestKeySet_Multi(t *testing.T) {
 	})
 	require.ElementsMatch(t, vs, [][]byte{[]byte("baz"), []byte("quux")})
 }
+
+func TestKeySet_DuplicateKeys(t *testing.T) {
+	ks := index.NewKeySet([]byte("baz"), []byte("quux"), []byte("baz"))
+	require.EqualValues(t, "baz", ks.First())
+	require.True(t, ks.Exists([]byte("baz")))
+	require.True(t, ks.Exists([]byte("quux")))
+	require.False(t, ks.Exists([]byte("foo")))
+	vs := [][]byte{}
+	ks.Foreach(func(bs index.Key) {
+		vs = append(vs, bs)
+	})
+	require.ElementsMatch(t, vs, [][]byte{[]byte("baz"), []byte("quux"), []byte("baz")})
+}
diff --git a/part_index.go b/part_index.go
index c227a98..917ffea 100644
--- a/part_index.go
+++ b/part_index.go
@@ -367,10 +367,7 @@ func (r *partIndexTxn) reindex(idKey index.Key, old object, new object) {
 					if !unique {
 						oldKey = encodeNonUniqueKey(idKey, oldKey)
 					}
-					_, hadOld := r.tx.Delete(oldKey)
-					if !unique && !hadOld {
-						panic("BUG: delete did not find old object")
-					}
+					r.tx.Delete(oldKey)
 				}
 			},
 		)
diff --git a/part_index_test.go b/part_index_test.go
new file mode 100644
index 0000000..59283e2
--- /dev/null
+++ b/part_index_test.go
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Authors of Cilium
+
+package statedb
+
+import (
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/cilium/statedb/index"
+)
+
+type partIndexDuplicateKeyObject struct {
+	ID   uint64
+	Tags []string
+}
+
+func (partIndexDuplicateKeyObject) TableHeader() []string {
+	return []string{"ID", "Tags"}
+}
+
+func (obj partIndexDuplicateKeyObject) TableRow() []string {
+	return []string{strconv.FormatUint(obj.ID, 10), strings.Join(obj.Tags, ",")}
+}
+
+func TestPartIndex_ReindexDuplicateKeys(t *testing.T) {
+	idIndex := Index[partIndexDuplicateKeyObject, uint64]{
+		Name: "id",
+		FromObject: func(obj partIndexDuplicateKeyObject) index.KeySet {
+			return index.NewKeySet(index.Uint64(obj.ID))
+		},
+		FromKey: index.Uint64,
+		Unique:  true,
+	}
+	tagIndex := Index[partIndexDuplicateKeyObject, string]{
+		Name: "tag",
+		FromObject: func(obj partIndexDuplicateKeyObject) index.KeySet {
+			return index.StringSlice(obj.Tags)
+		},
+		FromKey: index.String,
+		Unique:  false,
+	}
+
+	db := New()
+	table, err := NewTable(db, "part-index-test", idIndex, tagIndex)
+	require.NoError(t, err)
+
+	wtxn := db.WriteTxn(table)
+	_, _, err = table.Insert(wtxn, partIndexDuplicateKeyObject{
+		ID:   1,
+		Tags: []string{"duplicate", "duplicate"},
+	})
+	require.NoError(t, err)
+	txn := wtxn.Commit()
+
+	require.Len(t, Collect(table.List(txn, tagIndex.Query("duplicate"))), 1)
+
+	var (
+		oldObj partIndexDuplicateKeyObject
+		hadOld bool
+	)
+	require.NotPanics(t, func() {
+		wtxn = db.WriteTxn(table)
+		defer wtxn.Abort()
+
+		oldObj, hadOld, err = table.Insert(wtxn, partIndexDuplicateKeyObject{
+			ID:   1,
+			Tags: []string{"replacement"},
+		})
+		if err == nil {
+			txn = wtxn.Commit()
+		}
+	})
+	require.NoError(t, err)
+	require.True(t, hadOld)
+	require.Equal(t, []string{"duplicate", "duplicate"}, oldObj.Tags)
+
+	require.Empty(t, Collect(table.List(txn, tagIndex.Query("duplicate"))))
+	objs := Collect(table.List(txn, tagIndex.Query("replacement")))
+	require.Len(t, objs, 1)
+	require.Equal(t, uint64(1), objs[0].ID)
+}