Generally, most online Duo CD images are pretty crappy.

If you do manage to track down a quality copy, Most PCE systems should
play them alright.

In my personal experiece, both my Turbo Duos played cdr's flawlessly
and even handled the crappiest downloaded games alright.

My Duo RX however, has trouble playing even the best cdr games and
won't really run downloaded games at all.

And the one white PCE CD-ROM that I've tried cdr's on didn't handle
them too well either.

But its not much of a problem, since 95% of PCE/Duo games ae now dirt
cheap and even Dracula X is only $75 - $150, which is what I was paying
for all PCE imports back in the day.

I'd suggest doing what I do with roms/emulation/video & music downloads.
Test the game out on your computer, and if ts worth it to you, go buy
the original to play on your hardware.