Tepper and Begley are the attorneys representing all of the named defendants in Mississippi, Obama is a named defendant.
You are correct that both Orly Taitz and Begley and Tepper are using the whitehouse.gov image of the long form as exhibits in this lawsuit.
The only difference is that the defense exhibit comes with a certified Letter of Verification from Hawaii.
Obama's counsel is Perkins and Coie. Obama is named, but so are individuals such as Nancy Pelosi, Alvin T. Onaka, Ph.D., Loretta Fuddy and others. I'm pretty sure those individuals who are out of state are not being directly represented by the MDEC's lawyers. If they were, then they could get an actual hard copy of Obama's LFBC and not a copy of PDF posted on a website with a vague letter of verification that lists no birth facts on it.