voelkx maybe yours was repaired, or someone upgraded it from R40 2.20 ROM to R30 2.50 ROM?

I'm nearly certain that the "R40" string is hardcoded in the ROM itself. They probably changed a few other things too, such as delay loop when writing to the LCD or speaker. But the chess engine should be the same. We won't know for 100% certain until the ROM dump surfaces.