My daughter's iPhone rings when I call my wife.
When I call my wife's iPhone my daughter''s iPhone rings at the same time, every time.
Since you seem to be using the same Apple ID account, make sure that you did not activate the option on that phone to receive phone calls as well in Settings/FaceTime/Mobile calls.
Same for the settings in FaceTime or Messages in "You can be reached at", only the one phone number belonging to the device should be marked.