Lincoln Wheat 1945: Filed Or Error?

I have been reading and enjoying your coin forums for quite some time, although this is my first post. In fact, I just registered yesterday because I found a Lincoln Wheat penny from 1945 that is a puzzle to me.

After spending a year sifting through rolls of old pennies, I ran across a 1945 that weighs only 1.85 grams. It seems also to be half as thick as a regular old copper penny.

In looking through your forums, I learned about the practice of filing down 1945 pennies to make them function as dimes in vending machines. I spent a few days trying to figure out how in the world this could have been filed down and concluded that there must have been some special method used to maintain consistency in stamping, thickness, etc, throughout when doing reductions.

As such, I decided to post here to see if anyone else has ever seen a penny like this. Perhaps it is an error or perhaps there really were some professional "filers" out there.

As I said, it is 1.85 grams and about half as thick as a regular Wheat penny. The stamping on the front seems pretty regular, but the back just looks so different. On the pictures below, especially of the fronts of two pennies (odd one on left and a normal 1945 on right), you can see the odd penny has a less distinct rim. The edge of the rim is not really as smooth as the regular penny and does appear to have the same type of pitting that appears on the back of the coin. This "pitting," however, doesn't really resemble any filing I have seen.

On the coin's back much of the smoothness one sees on the regular penny is gone. Instead, there seems to be consistent pitting (or graininess) in those areas. The type for ONE CENT is clear, but does not protrude as does the print on the regular penny. The words E Pluribus Unum and United States of America are there, but not clearly visible unless in the right light. Again, they do not protrude, but almost seem to be concave. All aspects of the wheats are visible.

Again, to the more experienced eye this may just be a penny that has been filed down. Perhaps there were machines used for filing that allowed for such amazing consistency and uniformity in reducing a penny to a dime size. I will appreciate any and all comments on this penny as it has me completely stumped.

Thank you in advance for your consideration of this matter.