This specimen of RRC 290/2 now in the Andrew McCabe collection (London) has something funny above the M on the reverse. What’s going on? I don’t see anything like on any of the other known specimens. Although I feel sure I’ve noted before on this blog or twitter the funny A like scrape on the obverse dies of this lovely Paris specimen.
(images from trade)
Liv Mariah Yarrow 
Could that be the starting “drill points” for an M? The (inexperienced/trainee?) celator may have realized he was too high up on the flan, without room for all of the RO and the A, then moved the M to be lower on the flan, leaving his error behind?
nice idea, McCabe will inspect specimen and report back