Fir & Fur

Seems like the right season for this one, doesn't it? Have a happy Life Day, everybody! ;)

Dual & Duel

With an A – an adjective referring to the number two, or, more specifically, to two aspects of a single concept/item.
With an E – also refers to the number two, but only as a fight or dispute between two people.

Or, for those who prefer things that happened a long time ago in a galaxy far, far away: