diff --git a/api/current.txt b/api/current.txt
index f62839e2d5414..e0c45e05c2754 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -15777,7 +15777,7 @@ package android.hardware.camera2 {
     method public java.util.List<android.hardware.camera2.CaptureRequest.Key<?>> getAvailablePhysicalCameraRequestKeys();
     method public java.util.List<android.hardware.camera2.CaptureRequest.Key<?>> getAvailableSessionKeys();
     method public java.util.List<android.hardware.camera2.CameraCharacteristics.Key<?>> getKeys();
-    method public java.util.List<java.lang.String> getPhysicalCameraIds();
+    method public java.util.Set<java.lang.String> getPhysicalCameraIds();
     field public static final android.hardware.camera2.CameraCharacteristics.Key<int[]> COLOR_CORRECTION_AVAILABLE_ABERRATION_MODES;
     field public static final android.hardware.camera2.CameraCharacteristics.Key<int[]> CONTROL_AE_AVAILABLE_ANTIBANDING_MODES;
     field public static final android.hardware.camera2.CameraCharacteristics.Key<int[]> CONTROL_AE_AVAILABLE_MODES;
diff --git a/core/java/android/hardware/camera2/CameraCharacteristics.java b/core/java/android/hardware/camera2/CameraCharacteristics.java
index 8502fc413c059..d5b052e485c4e 100644
--- a/core/java/android/hardware/camera2/CameraCharacteristics.java
+++ b/core/java/android/hardware/camera2/CameraCharacteristics.java
@@ -28,7 +28,9 @@ import android.util.Rational;
 
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 /**
  * <p>The properties describing a
@@ -450,23 +452,20 @@ public final class CameraCharacteristics extends CameraMetadata<CameraCharacteri
     }
 
     /**
-     * Returns the list of physical camera ids that this logical {@link CameraDevice} is
+     * Returns the set of physical camera ids that this logical {@link CameraDevice} is
      * made up of.
      *
      * <p>A camera device is a logical camera if it has
      * REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA capability. If the camera device
-     * doesn't have the capability, the return value will be an empty list. </p>
+     * doesn't have the capability, the return value will be an empty set. </p>
      *
-     * <p>The list returned is not modifiable, so any attempts to modify it will throw
+     * <p>The set returned is not modifiable, so any attempts to modify it will throw
      * a {@code UnsupportedOperationException}.</p>
      *
-     * <p>Each physical camera id is only listed once in the list. The order of the keys
-     * is undefined.</p>
-     *
-     * @return List of physical camera ids for this logical camera device.
+     * @return Set of physical camera ids for this logical camera device.
      */
     @NonNull
-    public List<String> getPhysicalCameraIds() {
+    public Set<String> getPhysicalCameraIds() {
         int[] availableCapabilities = get(REQUEST_AVAILABLE_CAPABILITIES);
         if (availableCapabilities == null) {
             throw new AssertionError("android.request.availableCapabilities must be non-null "
@@ -475,7 +474,7 @@ public final class CameraCharacteristics extends CameraMetadata<CameraCharacteri
 
         if (!ArrayUtils.contains(availableCapabilities,
                 REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA)) {
-            return Collections.emptyList();
+            return Collections.emptySet();
         }
         byte[] physicalCamIds = get(LOGICAL_MULTI_CAMERA_PHYSICAL_IDS);
 
@@ -485,9 +484,9 @@ public final class CameraCharacteristics extends CameraMetadata<CameraCharacteri
         } catch (java.io.UnsupportedEncodingException e) {
             throw new AssertionError("android.logicalCam.physicalIds must be UTF-8 string");
         }
-        String[] physicalCameraIdList = physicalCamIdString.split("\0");
+        String[] physicalCameraIdArray = physicalCamIdString.split("\0");
 
-        return Collections.unmodifiableList(Arrays.asList(physicalCameraIdList));
+        return Collections.unmodifiableSet(new HashSet<String>(Arrays.asList(physicalCameraIdArray)));
     }
 
     /*@O~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~@~
diff --git a/core/java/android/hardware/camera2/CaptureRequest.java b/core/java/android/hardware/camera2/CaptureRequest.java
index 98901a1e69190..d7c55645e20c2 100644
--- a/core/java/android/hardware/camera2/CaptureRequest.java
+++ b/core/java/android/hardware/camera2/CaptureRequest.java
@@ -808,7 +808,7 @@ public final class CaptureRequest extends CameraMetadata<CaptureRequest.Key<?>>
          *
          *<p>This method can be called for logical camera devices, which are devices that have
          * REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA capability and calls to
-         * {@link CameraCharacteristics#getPhysicalCameraIds} return a non-empty list of
+         * {@link CameraCharacteristics#getPhysicalCameraIds} return a non-empty set of
          * physical devices that are backing the logical camera. The camera Id included in the
          * 'physicalCameraId' argument selects an individual physical device that will receive
          * the customized capture request field.</p>
diff --git a/core/java/android/hardware/camera2/TotalCaptureResult.java b/core/java/android/hardware/camera2/TotalCaptureResult.java
index 0be45a0c9779f..4e20cb8d129ea 100644
--- a/core/java/android/hardware/camera2/TotalCaptureResult.java
+++ b/core/java/android/hardware/camera2/TotalCaptureResult.java
@@ -138,7 +138,7 @@ public final class TotalCaptureResult extends CaptureResult {
      *
      * <p>This function can be called for logical multi-camera devices, which are devices that have
      * REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA capability and calls to {@link
-     * CameraCharacteristics#getPhysicalCameraIds} return a non-empty list of physical devices that
+     * CameraCharacteristics#getPhysicalCameraIds} return a non-empty set of physical devices that
      * are backing the logical camera.</p>
      *
      * <p>If one or more streams from the underlying physical cameras were requested by the