I agree with xoft.
If you still want a server that is compatible with both 1.2.5 and 1.3.2 you should simply ban/block all the 1.3.2 features (perhaps by using a plugin)
If you still want a server that is compatible with both 1.2.5 and 1.3.2 you should simply ban/block all the 1.3.2 features (perhaps by using a plugin)