It is legally impossible for Squaresoft to "steal" from Squaresoft, therefore that argument is immediately discarded. Also, they have ALWAYS used the hero-villain act because it is a Final Fantasy T-R-A-D-E-M-A-R-K.
Examples:
Squall-Seifer
Cloud-Sephiroth
Zidane-Kuja(obviously)
Tidus-Seymore
