diff --git a/framework-t/src/android/net/NetworkStats.java b/framework-t/src/android/net/NetworkStats.java
index 0b5bb85..4f816c5 100644
--- a/framework-t/src/android/net/NetworkStats.java
+++ b/framework-t/src/android/net/NetworkStats.java
@@ -1147,7 +1147,8 @@
             entry.txPackets = left.txPackets[i];
             entry.operations = left.operations[i];
 
-            // find remote row that matches, and subtract
+            // Find the remote row that matches and subtract.
+            // The returned row must be uniquely matched.
             final int j = right.findIndexHinted(entry.iface, entry.uid, entry.set, entry.tag,
                     entry.metered, entry.roaming, entry.defaultNetwork, i);
             if (j != -1) {
@@ -1304,13 +1305,14 @@
 
     /**
      * Removes the interface name from all entries.
-     * This mutates the original structure in place.
+     * This returns a newly constructed object instead of mutating the original structure.
      * @hide
      */
-    public void clearInterfaces() {
-        for (int i = 0; i < size; i++) {
-            iface[i] = null;
-        }
+    @NonNull
+    public NetworkStats clearInterfaces() {
+        final Entry temp = new Entry();
+        return map(entry -> temp.setKeys(IFACE_ALL, entry.getUid(), entry.getSet(),
+                entry.getTag(), entry.getMetered(), entry.getRoaming(), entry.getDefaultNetwork()));
     }
 
     /**
diff --git a/service-t/src/com/android/server/net/NetworkStatsService.java b/service-t/src/com/android/server/net/NetworkStatsService.java
index e7ef510..6635fd3 100644
--- a/service-t/src/com/android/server/net/NetworkStatsService.java
+++ b/service-t/src/com/android/server/net/NetworkStatsService.java
@@ -1744,8 +1744,7 @@
             // information. This is because no caller needs this information for now, and it
             // makes it easier to change the implementation later by using the histories in the
             // recorder.
-            stats.clearInterfaces();
-            return stats;
+            return stats.clearInterfaces();
         } catch (RemoteException e) {
             Log.wtf(TAG, "Error compiling UID stats", e);
             return new NetworkStats(0L, 0);
diff --git a/tests/unit/java/android/net/NetworkStatsTest.java b/tests/unit/java/android/net/NetworkStatsTest.java
index 126ad55..4ff131b 100644
--- a/tests/unit/java/android/net/NetworkStatsTest.java
+++ b/tests/unit/java/android/net/NetworkStatsTest.java
@@ -1073,30 +1073,35 @@
         final NetworkStats.Entry entry1 = new NetworkStats.Entry(
                 "test1", 10100, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
                 DEFAULT_NETWORK_NO, 1024L, 50L, 100L, 20L, 0L);
-
         final NetworkStats.Entry entry2 = new NetworkStats.Entry(
                 "test2", 10101, SET_DEFAULT, 0xF0DD, METERED_NO, ROAMING_NO,
                 DEFAULT_NETWORK_NO, 51200, 25L, 101010L, 50L, 0L);
+        final NetworkStats.Entry entry3 = new NetworkStats.Entry(
+                "test3", 10101, SET_DEFAULT, 0xF0DD, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 1, 2L, 3L, 4L, 5L);
 
         stats.insertEntry(entry1);
         stats.insertEntry(entry2);
+        stats.insertEntry(entry3);
 
         // Verify that the interfaces have indeed been recorded.
-        assertEquals(2, stats.size());
+        assertEquals(3, stats.size());
         assertValues(stats, 0, "test1", 10100, SET_DEFAULT, TAG_NONE, METERED_NO,
                 ROAMING_NO, DEFAULT_NETWORK_NO, 1024L, 50L, 100L, 20L, 0L);
         assertValues(stats, 1, "test2", 10101, SET_DEFAULT, 0xF0DD, METERED_NO,
                 ROAMING_NO, DEFAULT_NETWORK_NO, 51200, 25L, 101010L, 50L, 0L);
+        assertValues(stats, 2, "test3", 10101, SET_DEFAULT, 0xF0DD, METERED_NO,
+                ROAMING_NO, DEFAULT_NETWORK_NO, 1, 2L, 3L, 4L, 5L);
 
         // Clear interfaces.
-        stats.clearInterfaces();
+        final NetworkStats ifaceClearedStats = stats.clearInterfaces();
 
-        // Verify that the interfaces are cleared.
-        assertEquals(2, stats.size());
-        assertValues(stats, 0, null /* iface */, 10100, SET_DEFAULT, TAG_NONE, METERED_NO,
-                ROAMING_NO, DEFAULT_NETWORK_NO, 1024L, 50L, 100L, 20L, 0L);
-        assertValues(stats, 1, null /* iface */, 10101, SET_DEFAULT, 0xF0DD, METERED_NO,
-                ROAMING_NO, DEFAULT_NETWORK_NO, 51200, 25L, 101010L, 50L, 0L);
+        // Verify that the interfaces are cleared, and key-duplicated items are merged.
+        assertEquals(2, ifaceClearedStats.size());
+        assertValues(ifaceClearedStats, 0, null /* iface */, 10100, SET_DEFAULT, TAG_NONE,
+                METERED_NO, ROAMING_NO, DEFAULT_NETWORK_NO, 1024L, 50L, 100L, 20L, 0L);
+        assertValues(ifaceClearedStats, 1, null /* iface */, 10101, SET_DEFAULT, 0xF0DD,
+                METERED_NO, ROAMING_NO, DEFAULT_NETWORK_NO, 51201, 27L, 101013L, 54L, 5L);
     }
 
     private static void assertContains(NetworkStats stats,  String iface, int uid, int set,
diff --git a/tests/unit/java/com/android/server/net/NetworkStatsBaseTest.java b/tests/unit/java/com/android/server/net/NetworkStatsBaseTest.java
index a058a46..2c9f212 100644
--- a/tests/unit/java/com/android/server/net/NetworkStatsBaseTest.java
+++ b/tests/unit/java/com/android/server/net/NetworkStatsBaseTest.java
@@ -41,6 +41,7 @@
 abstract class NetworkStatsBaseTest {
     static final String TEST_IFACE = "test0";
     static final String TEST_IFACE2 = "test1";
+    static final String TEST_IFACE3 = "test2";
     static final String TUN_IFACE = "test_nss_tun0";
     static final String TUN_IFACE2 = "test_nss_tun1";
 
diff --git a/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java b/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java
index b8b0289..6292d45 100644
--- a/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java
+++ b/tests/unit/java/com/android/server/net/NetworkStatsServiceTest.java
@@ -1250,8 +1250,9 @@
                 TEST_IFACE2, IMSI_1, null /* wifiNetworkKey */,
                 false /* isTemporarilyNotMetered */, false /* isRoaming */);
 
-        final NetworkStateSnapshot[] states = new NetworkStateSnapshot[] {
-                mobileState, buildWifiState()};
+        final NetworkStateSnapshot[] states = new NetworkStateSnapshot[]{
+                mobileState, buildWifiState(false, TEST_IFACE, null),
+                buildWifiState(false, TEST_IFACE3, null)};
         mService.notifyNetworkStatus(NETWORKS_MOBILE, states, getActiveIface(states),
                 new UnderlyingNetworkInfo[0]);
         setMobileRatTypeAndWaitForIdle(TelephonyManager.NETWORK_TYPE_LTE);
@@ -1266,16 +1267,22 @@
         final NetworkStats.Entry entry3 = new NetworkStats.Entry(
                 TEST_IFACE, UID_BLUE, SET_DEFAULT, 0xBEEF, METERED_NO, ROAMING_NO,
                 DEFAULT_NETWORK_NO, 1024L, 8L, 512L, 4L, 2L);
+        // Add an entry that with different wifi interface, but expected to be merged into entry3
+        // after clearing interface information.
+        final NetworkStats.Entry entry4 = new NetworkStats.Entry(
+                TEST_IFACE3, UID_BLUE, SET_DEFAULT, 0xBEEF, METERED_NO, ROAMING_NO,
+                DEFAULT_NETWORK_NO, 1L, 2L, 3L, 4L, 5L);
 
         final TetherStatsParcel[] emptyTetherStats = {};
         // The interfaces that expect to be used to query the stats.
-        final String[] wifiIfaces = {TEST_IFACE};
+        final String[] wifiIfaces = {TEST_IFACE, TEST_IFACE3};
         incrementCurrentTime(HOUR_IN_MILLIS);
         mockDefaultSettings();
-        mockNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 3)
+        mockNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 4)
                 .insertEntry(entry1)
                 .insertEntry(entry2)
-                .insertEntry(entry3), emptyTetherStats, wifiIfaces);
+                .insertEntry(entry3)
+                .insertEntry(entry4), emptyTetherStats, wifiIfaces);
 
         // getUidStatsForTransport (through getNetworkStatsUidDetail) adds all operation counts
         // with active interface, and the interface here is mobile interface, so this test makes
@@ -1293,7 +1300,7 @@
         assertValues(wifiStats, null /* iface */, UID_RED, SET_DEFAULT, 0xF00D,
                 METERED_NO, ROAMING_NO, METERED_NO, 50L, 5L, 50L, 5L, 1L);
         assertValues(wifiStats, null /* iface */, UID_BLUE, SET_DEFAULT, 0xBEEF,
-                METERED_NO, ROAMING_NO, METERED_NO, 1024L, 8L, 512L, 4L, 2L);
+                METERED_NO, ROAMING_NO, METERED_NO, 1025L, 10L, 515L, 8L, 7L);
 
         final String[] mobileIfaces = {TEST_IFACE2};
         mockNetworkStatsUidDetail(buildEmptyStats(), emptyTetherStats, mobileIfaces);