I've solved this without having to resort to uninstalling the alternate apk first (what a pain, right?). To successfully install both a debug and release version of an apk, simply use gradle's built-in ${applicationId} placeholder within the AndroidManifest.xml to modify the permissions' android:name values at compile time.
The build.gradle file snippet:
buildTypes {
debug {
applicationIdSuffix ".debug"
...
}
}
The AndroidStudio.xml file snippet:
<uses-permission android:name="${applicationId}.permission.C2D_MESSAGE"/>
<permission
android:name="${applicationId}.permission.C2D_MESSAGE"
android:protectionLevel="signature"/>
You can inspect the modified AndroidManifest.xml file within the apk using aapt l -a app-debug.apk
to ensure the placeholder was properly applied. If you use various product flavors, I'm sure you can apply a variation of this method to suit your needs.