It does not make any sense, mate. If you're saving as, you are saving a copy of the whole FLA under an new name, but are not changing anything in the internal structure of your file. To get those duplicates of your content internally, you must be doing something else, while working in Flash. Check their use count in the Library. If some have zero, you can delete them. There is an option to select unused items. If they really are duplicates and they are all used, to clean them up you will need first to do some swapping so that only one of those identical videos and bitmaps is used in your file.
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