Multi Android devices vs NameMapping

I have to run the same tests on different hardware devices. I have the harware devices and a usb hub connected to my PC. 

I have mapped everything I need to run my tests.  It does run fine when one device is connected.  When a second device is running my mobile app, I get Ambiguous recognition on the "Aliases.Android.Process_myapp_abc".  I do not necessaraly want to uninstall the package after running my tests since manual testing sessions might follow.

Is there a way to "stop the app" on the current device?

I have tried the "close" and the "terminate" methods without success. The idea is to have only 1 of the devices running my app at a time to avoid the "ambiguous" warnings.  Note: disabling the warning does not help since it will execute the scripts on the first device it finds in windows...

Thanks