Coinsandcanada.com

There is mule version of the 1858 Province of Canada 20c that has the obverse of the intended coin (>700,000 minted) and the reverse of the 1862/4 New Brunswick 20 cent. It's a very interesting little freak of a coin. I've seen a few of them appear on eBay (Proof Positive has one there now for $15,000) and at various auctions. They generally command very high prices but I have no idea whether they're actually worth it in terms of scarcity. They tend to be high grade because I think they were produced exclusively as specimen coins and not ever circulated.

Does anyone know how many of them were minted? Is that number known?