Oh, that is a simply delightful concept. The mechanics do need a bit of thought though, depending on how you rule the Multitasking augment works. The most simple version would to rule that it has two inbuilt cyberbrains, and so all the character needed to do is disable the automatic merge/fork functions, converting the augment into a pair of ghostriders. This is simple, but also a tad boring. In my mind, the forks from the MT-Aug aren't complete, but instead share critical components such as memory with the Alpha. This would, however, preclude personality drift beyond psychosurgical overlays. Imo the most interesting version is if the character has given himself (either through messing with the implant or through purposeful psychosurgery) a very mild case of Multiple Personality Syndrome, which only triggers through the use MT-Augs. At it's most basic, this could simply be a Neutral Trait, but is a perfect excuse for the character to possess +/- traits such as Hardening (Isolation) or Anomalous mind. If you're willing to go full houserule, then I'd propose allowing him to always act as if he had a MT-Aug, as long as he applies the cost of the blueprint with his +Trait limit.