I did a search for wrong messaging contact and even just wrong contact and didn't get any worthwhile results, so here goes...
I use only the stock messaging app. A lot of times the app works fine. Then sometimes when you go into the app in the root thread messaging view, it might list the same contact twice. When I go to the mislabeled contact and go into the thread, the name at the top is CORRECT, but the names for each of their text messages is the INCORRECT name. After awhile it fixes itself.
What's the dealio?
I don't want to download a different messaging app. I like the stock one, I like that I am not wasting space or memory using a third party app that I don't use one iota of the features.