Can I apply to both MIT & Yale in Early Action ? Besides Does applying Early offer any advantages ?
No, you cannot apply early to both. Yale has “single-choice early action”, which prohibits you from applying early action to other universities. (There’s exceptions, but none of them applies to MIT, which is a direct competitor to Yale.)
http://admissions.yale.edu/faq/single-choice-early-action
As to advantages: Some universities have higher admission rates in the early admission rounds. I don’t know if Yale or MIT are among them. In any case, applying early forces you to get your application materials ready and will help you stay on top of the application process.