I just watched a video that appeared on my YouTube homepage called "Russian Bootleg Nintendo Games" (
https://www.youtube.com/watch?v=nB12ILnm5eM). I noticed two things about it; firstly, the guy playing used the Retron 5, making everything a glitchy mess...even though he has a Dendy and Micro Genius in the video. Great job. But more importantly, two of the cartridges shown were branded as "Dendy Junior" on the front, and are clearly test cartridges of some kind. One of them (seen at 7:08) has a handwritten label, and loads a screen with the Dendy elephant and says something along the lines of "Please connect your Dendy network adapter". The other cartridge (seen at 16:30) has no label, and loads a blank screen with Duck Hunt sounds (and flashing Duck Hunt's background covers whenever they appear). Has anyone ever seen these before, or know where they were used?