I've never heard of an S over D LMC. Yours looks like it took a hit or something or maybe a die chip. Hard for me to tell with the blurry pictures.
Sorry about that. The coin shows no signs of chipping but it clearly looks like an S punched over a D. I am new to collecting but I know what errors to look out for. That's pretty cool that they are unheard of to you. I really think I should get it checked out.
Before you waste your money sending it to NGC get a better picture and post it here. I know a decent amount about Lincoln's but I am by no means and expert. There are others on here who are much more knowledgeable than me. I'm sure they will agree with me.
From angles, it is a clear S. Looks as if there was no D. There is also what seems to be part of something coming out the sides as well
Come to find out, d.t.menace is correct. I further inspected the coin and the D was hit from the SW. I do however have a different error coin I would like to get opinions about.