It's a 2011 coin. With v2 hologram and loaded in 2012.
Or a 2012 coin with a 2011 token. As you want to see it
It's one of the few ones in the 2012 stats.
I wouldn't consider that a "loading error."
There are quite a few Casascius coins that were loaded later than the date marked on the coin, some even have 2-3 year discrepancies.
I might be wrong but my opinion is that this is worth 2-3
BTC at most. I've only seen a premium paid for first roll and first funded coins. Best of luck with your sale though!