Transfer posts from one user to another

Some reason during my transfer to IP.Board 4.x I have several posts that are listed under dennis-56 and others listed as just dennis which is correct.

Does anyone know of a MySQL search and replace type feature (find dennis-56 and replace with dennis) to help clean up my site?  Of course this is just an example, I have several instances of this same thing that happened and would like to fix the whole site but figured if I could get some help fixing dennis I could fix the rest using the same example.