DEFDAM - Definitely Damaged. Circulation wear and tear Damage. Not a mint error of any kind. There is copper in between the clad layers. That's why it looks like copper as you stated in your poll. All clad coins have a copper core.
I think the clad layers are missing making it weigh 1.9 minus 0.9 for both clad layers from 2.3 to 1.9 grams
Missing clad layer usually occurs on one side. You have Environmental damage to the clad layers. Not a mint error of any kind. Corrosion to the clad layer can lead to a lesser weight. Here are examples from my collection - Mr. Ed (Specializing in collecting mint errors since 1985)
If both clad layers were missing, it would weigh even less and be thinner. It would be incredibly rare and unusual for just the copper core to be struck. Generally it's on one side only. And the side without the clad can be a nice bright copper color with very sharp details. Your coin is damaged, circulated, etc. It's possible it was even put in acid, which will reduce the weight.
