iphones sharing recent contacts

I am trying to figure this out, and I can't find the obvious reason.

My wife and I have iphones. Her's is a 5c, mine a 5. i only use icloud on each for backups.

I do not sync contacts for either phone, to the cloud. I have in the past, but not in some time.

we have separate accounts to handle imessage.

Basically...unless I missed a check box somewhere....they should not really be linked.

So what is happening, is if I go to text someone, and say I start typing in "T", I see a whole bunch of contacts-many of which are on her phone, and whom I've never texted. they aren't in icloud. I cannot, for the life of me, figure out why i am seeing any of her recently texted numbers-and vice versa.

when they come up, my options are of course to text them, or i can click on the i in the circle next to the name/number and "remove from recents". which I've now done for a number of them.

my questions are twofold.

1-What must I do to prevent this going forward? my phone is a work phone, and I have a huge number of contacts. My wife won't want to have all of them popping up in her recents.

2-If I remove them from my phone's recent contacts....is the change shared with her phone, or is it something I have to repeat from her's as well

thanks in advance