If you have already used your muzzleloader tags, then you cannot legally kill another doe. You cannot tag an animal with a tag from another season. I have to read the regs, but you might be able to have someone else sign their tag over to you to use, but please check this out first. I know that you are only asking a hypothetical, but we all need to follow the game laws and ethics to preserve our hunting future. All it takes is one such story to hit the papers, and we all look bad. I'm not preaching, but I think that you all will agree.
PS- I hope that your season goes well enough to need more tags!
K.K