The only problem I can think of is the fact that both scripts rely on a main file called arcade.php.
I think you have to install both in the root of your forum, so to circumvent this you could rename arcade.php for one of the 2, and change all calls to this script to the renamed version.
Ibpro has around 140 points where it calls the arcade.php file, V3 about 85.
I'm not sure if the 2 have identical sql table names etc. Just try it with wamp/xamp etc.