I'd call this casting flaw
scarce. Definitely not
rare.
In my experience, they are not generally picked out of
bulk lots. They are found, as could be expected, on the high volume coinage.
I did a quick check, and of my legible reverses I have 5 on Tang Kai Yuan coins, 4 on value-1 Northern Song, and 2 on value-2 Northern Song.
Admittedly, not all have as severe a dislocation as yours. Maybe 1/3 of mine do and the other 2/3 have less dislocation.
I have even seen rubbings of ones where the
reverse has parts of two coins on it.
Definitely worth highlighting in a sales listing though, in my opinion, as they are
still an interesting evidence of a casting flaw.
SC
