could someone let me know if this is a repunched mint mark
its on a 1975 D Lincoln penny
It could be a delamination, or raised metal from an impact below the mint mark.
Normally a RPM has the same shape and orientation as the main mint mark (and sometimes at 90 degree rotation).
Post minting damage with corrosion.
That would be PMD.... now the zinc is corroding a bit and surface is misshapen. Cheers, RickO