Lincoln Memorial Cent Brockage Error

This might make it easier to understand. "Struck Coin" is redundant, you either have a planchet (unstruck) or a coin (struck). A brockage error can happen on any planchet (thin, split, clipped, or standard) so weight isn't an indicator. It doesn't need to stick to the dies either though that is a common way to get brockages. This coin, which was either a split or thin planchet, was fed into the press with another planchet and was struck. Therefore it is uniface (only one side die struck). The design on the obverse is a bleed through of the reverse strike.

There is lots of info on Error-ref.com to read through and it is where we get most of our error information: https://www.error-ref.com/?s=brockage

Very nice error!

Thanks to all that have answered so far. I went to the company I retired from yesterday and was not able to use the microscope there to take photos. It is currently out of commission. Same for the XRF where I was hoping to confirm the alloy of this coin and of a Civil War Token I have.