Can I cook something twice in sous vide?

Yes you can do this. The important thing to do is quick chill your steak in an ice/water bath. This helps limit the time that the steak is in the danger zone.

Cey

Would this effect quality at all?

The quality shouldn't be affected at all. Many top-notch restaurants use this technique.

Just be sure you quick chill the food for safety, it should be about a 1 to 1 mixture of water and ice (not just a few cubes floating in bowl of water).

Sometimes I'll also cook it, quick chill it (or remove it from the vacuum, which also kills the dangerous bacteria). Once I'm ready to serve it later that week I'll take out of the pouch (if I hadn't before) and treat it as I would non-sous vide food. So I'll let it warm up for 30-60 minutes on the counter, then sear it in a hot pan. I've found I can get a real good crust on it this way before the middle heats up, and really, you only need the middle to get up to 100-120°F since it's already cooked through.