Q: multiple iPhones ringing

Even though Facetime may be turned off, I would still go to Settings > FaceTime and change "iPhone Cellular Calls" to off on both phones.  Then do a restart/forced restart:

Restart your iPhone, iPad, or iPod touch - Apple Support

Note: If both of the phones are yours and you want to use the same Apple ID, that's OK.  (Normally you would want both phones to ring if either gets a call for you.)  However, if there are  two different users for these phones, each user should have their own Apple ID.  If that is the case and you want to share content, then consider using Family Sharing:

Family Sharing - Apple Support