In Appalachia we often add the word in to our sentences even when it's unnecessary.
- He said he saw the biggest bear he ever seen in above Pap's house.
- Charlene dropped her earring and we liked to have never found it. I got the flashlight and then we saw it laying right in under the tv.
- He used to have a ole lean-to right back in against the hill over there.
- Just walk back in behind the school house and you're sure to see the mess they made.
I think we add the word in to our sentences for emphasis. Whatever the reason-it would be impossible for me to remove the unnecessary ins from my speech even if I wanted to.