Fake Rotated Die Error Kennedy Half

I posted about this coin on the coin roll hunting thread, but I thought it might be of interest to error collectors as well.

I went through about $240 in halves the other day and found absolutely nothing, until I got to the last roll. Those were all common clads, except when I performed my "coin turn" to check the reverses one 1971-dated coin had a 100° clockwise rotation. For about 2 seconds I was stoked, but then I spotted the telltale reverse seam of a fabricated rotated die error. Someone had hollowed out the back side of a 1971 coin and shaved down another half to fit inside. They positioned the filler coin with the reverse in the rotated position. It was precisely done, but the seam is easily visible around the reverse rim. This is the second fake rotated die half I've found while roll hunting.

There are actually 4 different indicators that this is a fake and not a genuine (and valuable) rotated die error:
1) The visible reverse seam.
2) The weight: a normal clad half weighs 11.34 grams; this one is about 10.8 grams.
3) The "ring": if you drop this coin on a table it mades a dull thudding sound. There is no ringing sound like you get with any normal coin.
4) The reverse is clearly not a 1971. I've seen enough Kennedy half dollars to know that on the 1971 coins the eagle is struck in relatively high relief. Detail is often soft, but the bird is three-dimensional. This coin has the low-relief reverse that you see on coins from the mid-nineties.

Anyway, it's a "fun" find, but I'd really rather have found just one 1964 silver!