ABNC specimens were nearly always marked "Specimen" in red. Proofs typically had small punch cancels, usually through signatures. I still think this is an example of sun fading, probably from being in a frame for a long period of time -- which is why the back still looks good. The first image you posted does appear to show some yellowing of the paper, but what clinches it for me are the security planchets. Those are the little colored dots embedded in the paper that look like confetti. They are multi-colored in the comparative ticket image from Heritage; in your ticket they all appear to be a dull gray. Working from digital images it's not possible to be certain, but that's what I'm observing. The set of six that paddyman posted appears to confirm that the blue and purple ink (on the Franklin ticket) was the most likely to fade away. Those six all look yellowed and the planchets are mostly faded.