Appears to have been gold plated at one time. If so, the value is what someone is willing to pay. IMO but I could be wrong. Allow others to chime in.
The left one is dated 1869 and it's been gold plated. The right one is dated 1865. Neither one is a proof.
From your photos it looks like it was plated and now it's wearing off. Who knows why but plating is a fairly common thing. The most famous plating on a coin was the Liberty or V Nickel. Look it up as it fascinating.
@Kevin Farley. Welcome to Coin Talk. Look on eBay and see how many plated coins are for sale. Most, if not all, collectors consider a plated coin as damaged.
Same reason as the nickel - There is nothing on these coins that say CENTS. So they were plated and attempted to be passed off as 3 dollars.
Probably wouldn't have worked very well, the size difference was way too great. It worked for the racketeer nickel because the nickel was 21.2 mm in diameter and the half eagle was 21.5 mm. The three cent nickel was 17.9 mm in diameter and the three dollar gold was 20.6 mm.
I don't know about gold plated. But, it looks like it was some kind of "gold wash". Agree with post #10: And perhaps they tried to pass it off as a 3 dollar gold coin.
Could be. There are a lot of new members and based on their questions, I would surmise many are young...
Well considering 3 dollar golds will cost them over $1000 apiece and up, if they are will to drop that kind of money on something they can't recognize, then Caveat Emptor. If they ask first I'll be happy to help them anyway I can, but if they buy first and ask questions later I'll advise, but I won't feel sorry for them.