I have a number of paper pieces here in my collection from different genres that have weathering/fading/discoloring on both sides. It's not always weathering exactly but fade or discoloring from the acids and such in the paper when stacked between other paper items. Whatever items are on top and bottom of it often affect the paper in between even when stored in a dark cool place. Bottom line is we can all sit here all day with our glasses half full or half empty about it. Until it is tested or one of us has it in hand it's hard to tell for sure. I hope it is authentic for the OP.