I experienced something similar to this and the cause of it:
I selected a contact, Nathan, and clicked the option for text message. The text message screen came up but with another contact's name, Bob, at the top of the message.
I sent the text which did go to Nathan but his reply even said it was from Bob.
I figured out the problem was that I accidentally had the same phone # in my contacts for Nathan and Bob. So for the texts to and from Nathan #'s, when google did a lookup of the phone # to my contacts it saw Bob before Nathan so it displayed Bob's name for that phone #.
Make sure there are no duplicate #s under different contacts, it may weird things out. Like, Mom - Home Dad-Home, 2 different contacts with the same # I think google pulls the first name from the contacts for ID lookup.