Question Concerning W/F Coil Paste Up Pairs

I am wondering what kind of adhesion was used to connect the strips of W/F coils to make a paste up pair. I have a used single of Scott #412 that still has the tab on the stamp, albeit it the stamp is soaked off the original paper. Can one soak off a used paste up pair without separating the 2 stamps?
I was looking at a potential purchase of a used #445 paste up pair....comes with a clean cert just that the back side is quite ugly with a hinge remnant, ect. Wondering if soaking will separate the two.

They are held together with the normal gum on the back of the upper stamp sticking to the front of the selvedge piece. Soaking will cause them to come apart.

If you apply sparingly hinge remanent remover just to the hinge you, might be able to lift it.

Here is a used paste up single of Scott #412. It looks to be soaked as normal and the tab is still in place. Looks like the tab was recemented on.