I don't know if this has happened to you, but I'm in the middle of making the same mistake twice...and on the same variety. I 'discovered' a coin which couldn't possibly be an existing variety and put in a bid accordingly, hoping no one else would see it. After placing the bid, I discovered to my chagrin, that it was just a common variety with missing diagnostics due to wear and corrosion. The rediscovery always happens AFTER I place my bid so I hope it doesn't get out of hand because I now have committed to paying up to three times the actual coin's value. And it's a coin I already have from the last time I made the SAME mistake. But at least I have learned a new diagnostic for the variety. Of course if this sounds like incoherent rambling, you probably aren't a lover of old copper. My soon to be NC-6 is just another S-65. The new diagnostic is the lack of any berrys between the Leaf and Wreath. The other varieties which share Obverse 32 have berrys there. Once again the fraction bar seems to vary from example to example. One which I use for comparisons seems th show little gap between the fraction bar and the denominator numbers, where both my mis-attributions and other comparison coins show the fraction bar high. It appears to be a sign of wear, rather than die variation.
Been there done that. I think the funniest one I did was on a graded coin from a dealer I had bought from before. First the coins was a date and had the look I liked so I wanted it anyway. This seller does not list variety and I always try to determine the variety to help me figure out what I might bid. The obverse matched something like 1826 N-5, but the reverse came closest to something like an N-6. I could not like the obverse and reverse up for nothing. Sure enough get the coin and it is an N-5. That was when I discovered the reverse picture on the auction matched the coin color wise, but not diagnostic wise. What fun it is at times.
I won this at ~$170. Fortunately the obverse is much better than the reverse. I had bid $519.58 which would have REALLY hurt. I could have sworn the stem was from the side of the leaf like the NC-6 at the time. Only later did I realize that there was a berry between the leaf and wreath on both the NC-6 and the S-64. The Holmes example wasn't very helpful with this one.
