I have to do a lot of primer and probe purification with Amicon filter. I heard that I can use it several times for proteins but I don't know if it could be applied for oligonucleotides as well.
Yes they can be reused BUT I'd stick with the same oligo if you care about cross contamination as they are difficult to really clean. These spin filters sometimes crack if allowed to dry without a "wetting agent " like glycerol, so be sure they aren't compromised before reuse. Good luck!