I can say that I tried both my Multi Game Hunter and Double Pro Fighter and neither worked.
But, both of these are very touchy about insertion and often take a couple tries to get to boot properly in my SNES. Since the Retro Duo is a completly different shell size, neither sit flush on the unit and require a lot of work to get to sit level on the unit.
I used a SuperCom Pro. 1 on my RetroDuo and FC Twin no problem, even though the cartridge slot is a lot shallower in the RetroDuo, so it doesn't sit very well on top the system. I really don't see why a copier unit would not work on Super NES clones. Hell, they even work without a cartridge because the clones lack a lockout chip.