Phone calls going to both iPhones, iPhone 5s & iPhone 6

My wife and I both have our iPhones on one family account. Since I upgraded to the iPhone 6 we have both been receiving all incoming calls on both phones. I have looked up how to fix this and have followed all suggested steps. I have made sure that the Facetime settings aren't set to include both of our numbers, I have checked every other phone setting on both phones and can't see where either of our numbers are checked on our phones.

Anyone have any ideas?

It's most likely your cell phone provider forwarding both phones to each other you need to go to your cell phone provider and have them correct this.

Cell provider couldn't figure it out. Apple suggested I go into FaceTime options and not only check to see which numbers are "checked" but also disable the "iPhone Cellular Calls" tab

Even with FaceTime options turned on, an incoming call should not be directed to both phones. There's something going on with your cell provider, either as John suggested or maybe your sim card is messed up. You say the problem started when you upgraded to the iPhone 6, and that should be a clue since your carrier would have to activate the phone. You didn't mention which carrier - but if you're using Verizon or Sprint, the sim card is not used.

Its through AT&T. They looked at all the specs of both phones when I spoke to them this morning. I will try going to a store next and having someone actually look at phone.

I don't closely follow the technicalities of cellular technology at the carrier level so disregard the following if it is a stupid question. Could the sim cards in both phones have been assigned the same phone number? I can actually think of instances where that might be desirable for some folks.

That's a good idea, let AT&T look at it. I have two phones here (T-Mobile) which are identical to the AT&T phones since both use GSM. I don't have that problem - when my iPhone receives a call it's only to my device. Same with my wife. And I have FaceTime turned on for my contacts both on the phone and my Mac.