Jesus lived in 00.00 AD. Muhammed came forth a few centuries later.
How, you ask, could one person be two people, especially when Muhammed was born 400 years later? For your theory incorporates the stupendously maniacal idea that Jesus could have lived past the age of 400 years.
Ah, but thats just what I am saying. The fellow was an immortal remmeber?
So Jesus the immortal lived on for how long? Who knows?
but if he was an immortal, then chances are he went upon the middle east 400 years after his original name of jesus, under a new name muhammed he created islam.