It's been struck through a very late stage die cap - the cap struck so many coins that it thinned out (while forming the walls of the cap) and was so thin that the design actually came thru the thin shell, and impressed onto the coin. For this die stage, picture a Die with a thin piece of wax paper over it - when struck, the image of the die will come thru, but will be 'softened' by the thin layer of wax/plastic paper - same effect as is shown on the coin above - one of the latest stages I've seen.
Fred, what's odd when I first saw this was that just above LIBERTY, is another LIBERTY though faded out and elongated (?) from right to left. Is this normal? or am I just seeing things for a late stage die cap.
It's a 'shifted die cap', that's why Liberty is there twice. The thin capped piece shifted at some point, and it was struck again, then imparting that design to the next group of coins struck. Scarcer than the non-shifted type, but not valued too much more, imo.