For starters, it seems like both of the obverse and reverse dies were struck on both sides of the coin.
I'm no expert in identifying error types, but I think it may be a double brockage.
On the reverse side of this coin, it seems like some 1974 nickel (already minted) has been stuck in the collar, and struck onto the reverse of the coin.
Similarly, on the obverse side of this coin, it looks like the reverse of the stuck coin has been struck onto the obverse of the coin.
I find it very neat how both dates 1973 and 1974 are on a single coin!
please let me know your thoughts on this. thanks!

