Can profiles play duels against each other?

No. Online duels match different accounts, and all profiles in a household share the same account: to the system, you are the same player. Even if you both manage to enter the same room, the game won’t work properly and no results will be recorded.

What you can do at home instead

• Ghost Duel: one of you records their run, and the other competes against that replay by switching profiles. This is the closest way to compete against each other.
• Compare scores in benchmarks: use the same reference text and see who gets the best speed and accuracy.
• Challenge friends who do have their own account, with the PvP Duel (Live).

Remember that online duels are part of the PRO plan; the Duel vs CPU is included in all plans.