Oh, so you purchased it?
You are right on both counts, but if it was dug
and later cleaned, oh well, its a bug hunk of silver!
The obverse was heavily cleaned, as indicated around the hole.
See the straight edge difference in tone there?
The darker tone difference is on most of the reverse.
And the wear of the coin seems right.
You have an authentic (slightly altered) Seated Liberty Half-Dollar!