Wife has a 2012 Edge and I recently bought a used 2010 Fusion and shortly after we got it home we noticed the key fob for the fusion actually locks/unlocks both of our vehicles.

Tried reprogramming keys for each car but the problem still exists.

What is the fix?

 

Welcome to the site.

Try reprogramming one set of remotes well out of the range of the other remotes/vehicle..
I've had that happen with remote entry and remote start installs..

 

Tried this tonight. Left my keys at home and we took the wife's car to a friend's house. Stopped at the gas station and while we were there I reprogrammed the keys for her car. When we came home I went inside and grabbed my keys, and my key still locks/unlocks both vehicles.

Would like to avoid having to take them to the dealer to fix this. Very annoying having to remember to lock her car ever
morning when I leave for work! 😠