After Reading fog's post, I went ahead and did another test...This time,using a 50/Hz PAL system LCD screen that I had in storage and that totally forgot about, since I don't have much use of it living here In the US (NTSC).....These were the results:
The SNES side worked ok with Ntsc SNES/SFC games...They run in full 60/Hz PAL mode...
Fog's description states that PAL system games work with it too....SNES multi-system compatibility perhaps???....
Now, when I tested the NES side with NTSC NES games running in the same PAL system LCD screen, the image was in the very common known incompatible Black & White screen....I don't have any PAL NES games for further testing, but it is quite possible that they'll work in PAL system tv's set ups (duh!...it'll make sense)....
Hopefully, fog or any other PAL user can keep us posted whenever they get to test some PAL NES games..,..
This definately gives the Retro Duo another extra point on my list!.....