what to do with same named .iff's

Lol noob question...was getting few things from Leftos' improving 2K guide... and the replay remover was a gamedata.iff... wanted to also add Jowe's redone sidelines/commentators... but it's also a gamedata.iff can you only have one and must choose between when loading the game or is there a way to add them both in...thanks for any help.

You can't add theme both. Take out what you want from one file and put in the other file.
This might help you: viewtopic.php?f=144&t=82787

specifically in that thread, look at the mod tool, and extracting/importing textures and models. You might also find these video tutorials useful - viewtopic.php?f=144&t=86557