Thanks Peckris, if proofs were double struck then the obvious candidate is the early obv die example here labelled cased proof -it appears to have been multiple struck or perhaps the die sinker was having a bad day!. They were all purchased as proofs with provenance built into the file identifiers used here. I expect some of these were struck to order much later than 1853 does anyone know if all those different obverse dies were available at the same time? My guess is once a new obverse was approved the older ones were no longer used.