What happened to the other Marty?

[whisky]

So its the end of Back to the future, the Marty we have been following arrives back in 1985 to find his family much more sucsesful, and he is the owner of a big black 4x4.

Only he isnt, the real owner was the Marty he watched in the parking lot going back to 1955.

That Marty lived the life the 1st Marty set up for him, but what the hell happened to that guy?

 

[CaptainWacky]

His memories were rewrote so that he "became" the only Marty. It just takes a while for changes to take effect in the Back To The Future universe.