Good brands of cable such as belden / excel / nexans / panduit manufacture cable so it exceeds standards such as TIA and ISO/EN standards.
Over a short run say 10 - 20 meters I have little doubt that the cable would not pass CAT5e certification meaning it will support 1000Base-T.
I'd say whether you use it should depend on the difficulty of the install. If you intend to chase it into walls etc, I would go out and buy some new cable. If however, you are just tucking it under carpets etc the CAT4 will more than likely be fine.
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