Nope… even rebooted the device that shouldnt be running notifications, nada.
But then I removed the offending notification widget from the project, and immediately put it back, and now all is well in the world of Gunner again 
Notification only on the correctly logged in devices.
So @wanek and @sh.abar.mard try simply removing and replacing the Notification Widget and see if that helps (until a fix is released).