Here is something interesting I found tucked inside a mint block file book. It looks like a crease between the center but it is not. The strip is stiff. I can pick it up by one end and it does not bend. There is no gum. My guess is that it was soaked off of something and dried with a wrinkle in the perf.

Have to handle it with care or it might become two pairs.
That will probably happen sometime in it's future.