Disturbed Gum--Used Or New But Flawed

The stamps in the pictures came in a group. Is there a definitive way to tell if they were removed from a postally used envelope or if they are postally unused and somehow the gum got stuck to other stamps in an album and left a mark when the previous owner separated them or if the previous owner got a sticky food on them, etc..?

Both appear familiar to me.
Stamps in humid environment have lightly fused
(The mucilage when given a rise in temperature loses its viscosity)

Later when the gum has reset, a handler of the stamps has tried to separate them. The results are quite common as you show.

The second scan, when seen in the middle of a stamp, could also be then a hinge "thin"

rod222: What does hinge "thin" mean?

Paper hinges are used to affix stamps to album pages. When a hinge is removed from a stamp it sometimes takes the gum with it.

Further to Stallzer's post.

The hinge when removed incorrectly will take the gum, and, part of the stamp paper as well, thus the paper is "thinned" and is seen held to the light, or under UV light.

Coincidentally, the one of the very reasons hinges came into being, not only to affix the stamp to the album page, but to hinge the stamp on an axis, so collectors could look at the back of the stamp without removal from the page.
'Hinge "thins" are considered

If you hold your examples with tongs, up against a light source, you should be able to see the "thin" yourself, from the front of the stamp.