I've ordered a few of Mama Bear's smaller "mug soap" size pucks. If I individually package each scent in it's own plastic bag, is there anything wrong with storing them in the same large jar, or will the flavors "migrate" like food in a freezer?
Assuming you use a freezer zip-top bag and one puck per bag I don't see where scent mixing would be an issue. If you store them in an unheated cabin in the north country or an unconditioned cabin in the south sometimes the pucks will soften (yes, with some soaps they are extremely soft after freezing) and be ruined because of that (it has been tried, there is a thread regarding this issue somewhere on here) but assuming your storage building is heated and cooled appropriately this method of storage should not be a problem.
One other comment for glycerin-based soaps -- do not attempt to heat them in a scuttle. They will melt (melting point is about 120 degrees F) and for about the second or third pass you will have liquid soap and not a puck.