dont know whats going on?

buyer bid on and won 2 lots of work pants. one lot size 82r then another lot 87r. i bundled with combined post. he unbundled and paid for i lot 87r. i messaged and asked why? he says he wants to see if they fit?? so then i go into order details and guess what???....same user name but 2 different names and addresses....what do you think is happening? anyway 82r lot is way overdue so i have opened a non paying case for them. also, when he gets them and tries them on and dont fit, do i have to pay for return post? also they are new with tags so what if they come back with tags off. i cant then resell as new 😞 im confused