Personally, I try to keep anything in their current state as best I can. The 'do no harm' thing. But in this case, I guess it depends on the size of the 'drop' of glue. One very tiny drop that fits outside the back border of the card will probably not do any more damage to the card than already exists. One 'drop' in the middle of the card the size of a thumbtack, probably a bit overkill. It should take the very smallest amount to hold them in place until framed.
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