I had it in my mind that I didn't own a 1878-CC Morgan. Found one in MS63 at a good price at a local coin show. Pulled the trigger and then found out I already had one. Oh well. Having another CC Morgan isn't a bad thing.
Trade it for another coin. Make sure you take your want list next time you go. We have all done this. I have a check list before I go to a coin show. 1. coin want list. 2. loupe/magnifiying glass 3. cash 4. something to put bought coins in. 5. take coins to show off to coin dealers and collectors friends I meet there. 6. take letter from dealer to get me in the show for free or a card saying free admission.
HAHA! I laughed because I have done the same thing recently with a 1981 PR69DCAM Susan B Anthony. I'm building a nice set in a Dansco album and I wanted to crack one out of it's tomb. I just recently bought one I was proud of and went to put it in my blue pcgs holder and BAM, there was another one staring right back at me! (So then I thought to myself, I need to get one of those binders that hold those slabs........ too many things to do , so little time).
If you find the duplicate eye appealing, IMO, it's not a bad thing to have more than one of a date and mm.
That's happened to me before too. What I would do is probably keep both for a while, take a good look at both of them, and then sell whichever one you don't think looks quite as good (assuming they're both MS63).
As long as I didn't overpay, that wouldn't irritate me as much as the fact that last weekend I bought a big bag of guajillo chiles based on remembering that I ran out a while back, but not remembering I had bought more until I tried finding a spot in the pantry for 3/4 of a bag of guajillo chiles.
