Yeah, well mine WERE invading demons...different entities from me, with different interests, personalities, and thought patterns. They even had different memories.
I mean, it makes about as much sense as somebody's mind (an intangible concept) being somehow fractured, or having more than one mind or spirit.
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)