ok so Stan’s features are not the same in each picture. The only “Stan” that’s features match the stan we know is the one where mabel and dipper go back in time and run past Stan’s shack as he looks outside and the 50s dancing in the 70s stan. All the other Stans have round ears and a square chin. While the stan we know has peanut shaped ears and a protruding chin. This makes me believe the glasses on the chart represent a different stan or a brother or even maybe represents Stan’s past life.
One other interesting thing is that in the ep carpet diem Stan sneakily takes a pair of glasses off the desk in the old abounded room. Then later in the ep we see Stan holding the glasses looking deep in thought. The glasses he is holding belongs to the Stan from the time traveling ep. These glasses must be the glasses on the chart with the other symbols. So this time traveling ep Stan must be the one it represents. He also has that dent in his chin that none of the other Stan’s have so this Stan could be a different person, a twin perhaps? Maybe Mabel and Dipper’s grandfather or someone Stan switched bodies with?