I contacted the auction house to ask whether they'd misstated the weight, and they responded that they hadn't and the coin was indeed genuine. The weight was due to a high lead content in the coin, which they stated was commonly done for the first few coins for a die. For me, that explained why the coin didn't seem in the best condition, so I put a low bid in that predictably didn't win. I later won a much better condition copy from a different auction house for the same winning price. However, I'm still wondering how common these "die starters" are. Are there collectors who focus on them? I searched and found no articles discussing this, but I'd appreciate any references/links.