res/drawable/module_2x2_layer.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/first_image">
      <bitmap android:src="@drawable/module_2x2_face_regular"
       />
    </item>
    <item android:id="@+id/second_image"  android:left="8dp">
      <bitmap android:src="@drawable/module_2x2_side_regular"
         />
    </item>
</layer-list>