Found this in some hand rolled rolls a teller sold to me. 50.00 bucks worth to be exact. She said this old guy brings them in every few weeks and she calls me when he does.
If the zinc one is not plated, then the copper plating has been removed. Need to see the reverse and the edge. But it's probably just damaged. If the weight is slightly heavy, (2.9) it could be a thicker rolled planchet.
Photo from post #4 seems as if the plating has been removed. Compared to the other coin in the photo.
2.9 grams is odd. Is your scale calibrated and zeroed? Weigh a handful of pre 1982 coppers and post 82 zincolns and see if your scale is off. Also, it would be better if your scale measured to the nearest 0.01 grams instead of 0.1 grams.