Elegant way to merge dicts without overwriting keys?

[Malcolm Greene]

I have a bunch of pickled dicts I would like to merge. I only want to
merge unique keys but I want to track the keys that are duplicated
across dicts. Is there a newer dict-like data structure that is fine
tuned to that use case?
Short of an optimized data structure, my plan is to convert dict keys to
sets and compare these sets to determine which keys are unique and can
be merged and which keys are dupes and should be tracked in that manner.
At a high level, does this sound like a reasonable approach?
Thank you,
Malcolm