I looked it up on PCGS and it looks like the 501 is only on proof coins, oops. Although this does look like a RPM of some sort...
If its flat and shelf like it's probably machine doubling. I know it's relatively common on quarters but I'm not so sure about nickels.
Since I cannot post a new forum I’ll put it here haha. I found this in an Americana Series collection on EBay for $20 a few years ago. Was curious about the crack or lamination error through the buffalo any opinions? Thought about sending it out for grading.