You mean other artists ripping off VIPER. That doujin wasn't published until 2004. RSR came out in 2002 and the other games like CTR and F50 were even earlier.
I wouldn't be surprised ot see other VIPER scenes used either as inpiration or an outright template for frames in the circle's other doujinshi. Quickly looking through them I think one could make the case for using scenes from Cyomi's and Akira's paizuri scenes.
Okay, that's quite the relief... i've must've read the original japanese post wrong, or something..
but that's great news...