The only reason I can figure that it only happens intermittently is that the linings will sometimes grab the shoes and the other times (when it makes the pedal bounce), the linings are spinning with the drum.Strange but plausible.
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If you do not want to have the drums turned and there is no pedal surging from out-of-round drums, I would suggest roughing the surface of the drums with sand-paper (LIGHTLY) to give the inner drum surface a break-in finish and not a shiney glassy surface from the previous shoes.
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I know this is not a by-the-book job as required by any brake service shop,but it will work good if the drums are not out-of-round or if they have an uneven wear surface(bell-shape).
.BE sure to inspect for cracks and or heat-checked(small cracks in the surface)or hot-spots on the surface.

There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!