I have never used Cupramine, but think it says to treat for two weeks? I've seen some people suggest three weeks. Even recall reading that if you call them, they will suggest three weeks. Odds are if you have done everything properly, they are both okay. For the one that still has a few spots on the tail, I would probably get it back in normal water and observe a little longer. No harm in taking a little longer just to be sure. Copper can cause damage to fish if exposed too long, so I'd go normal salinity, or even hypo. If the other is clear, it's probably good to go.