It might be of interest as we know that at least two incuse edge collars for crowns of this period were made. They weren't used on many patterns, but L&S lists 4 with an incuse edge that could apply (151, 186, 187 & 194), together with a 5th (184) that had an incuse edge but not of full height (clearly not applicable).
The collars wouldn't have been thrown away, so maybe the wrong collar was used, replaced and the coin restruck. The coin is a bit dire for research, but are there any hints of understriking anywhere else?