Plugins collide on Unity 5

After adding Play Games plugin for Unity I can no longer build my project:

Found plugins with same names and
architectures,
Assets/Plugins/Android/android-support-v4.jar
(ARMv7) and
Assets/Plugins/Android/libs/android-support-v4.jar
(ARMv7). Assign different
architectures or delete the duplicate.
UnityEditor.AndroidPluginImporterExtension:CheckFileCollisions(String)
UnityEditorInternal.PluginsHelper:CheckFileCollisions(BuildTarget)
(at
C:/buildslave/unity/build/Editor/Mono/Plugins/PluginsHelper.cs:25)
UnityEditor.BuildPlayerWindow:BuildPlayerAndRun()

Deleting ‘duplicates’ as suggested (well, they are not: one is 266kB and the one inside Android/libs is 634kB) causes another error:

Failed to re-package resources.

CommandInvokationFailure: Failed to
re-package resources. See the Console
for details. C:\Program Files
(x86)\Android\android-sdk-windows-u5\build-tools\21.1.1\aapt.exe
package --auto-add-overlay -v -f -m -J
gen -M AndroidManifest.xml -S “res” -I
“C:/Program Files
(x86)/Android/android-sdk-windows-u5/platforms/android-21\android.jar”
-F bin/resources.ap_ --extra-packages com.google.android.gms:com.google.unity:com.google.example.games.mainlibproj:com.example.project
-S “E:\project\Temp\StagingArea\android-libraries\google-play-services_lib\res”
-S “E:\project\Temp\StagingArea\android-libraries\unity-android-resources\res”

Plugin version: 0.9.20
Unity: 5.0.0f4

I’ve also created issue at Google Play Game Services · GitHub 5 days ago.

Updating plugin to 0.9.21 resolved the issue.