The people on this site who can properly answer your question will undoubtedly ask to see photos of your coin. Full obverse, full reverse and a close up of area of concern. Just so ya know.
There aren't any known. It is most likely die deterioration doubling. You can also attach a few pics so that we can help.
Sorry about no photos at this time I'm in the.middle of moving and will get some ASAP , Thank You for your patients