Hi all!

I went to an indoor flea market looking for some coins. I came across a cent marked "double Thumb". I took out my magnifier and checked it out. Did not see a Double thumb.

I hope that maybe someone can show me what it is that I'm looking for. I had not heard of this error, so was kind of interested.
I noticed this seller had quite a few mismarked coins in his display. Thanks for any info you can give!