I have some 10'- and 6'-long 25 gauge metal furring channels (hat channels) that have been used to hang drywall. I want to reuse them instead of getting new ones. There are about 10 screw holes per 4' of channel length. When I reuse it, I plan on adding 10 more holes per 4' of length. I don't think perforating the metal this much will reduce its integrity, but I just want to be sure.
Assuming the base material hasn't been somehow deformed, buckled, creased, etc., adding several small screw holes to the existing ones will not materially effect the channel's suitability for it's intended purpose.
However, if you are improving someone else's property, and they are expecting new material in their work, using salvaged material would be quite sleazy. If this your own property, you will have no difficulties.