This image makes a good point

http://www.thai-toku.com/cgi-bin/Y1Gold/tcsyabb/index.pl?board=general&action=display&num=1160527106

the first image. the simularitys are so close.

It's been like this throughout toku for a long time now. Rhino beetles and Stag Beetles are like yin and yang. Can't have one without the other. I'm not too sure though, but I think it may've been the B-Fighter series that started that