Why do some fighter jets have double wheels in the front gear whereas some other aircraft have a single wheel?
Ther are a lot of reasons for doing one over the other, from design trade offs to steering mechanisms to weight savings vs Service life, runway loading requirements, etc.  In the case of the Rafale-N, the nose landing gear is designed to interface with the catapult shuttle on the ship, so a single nosewheel would not be an option here.