number brother 

Not to be confused with number neighbor, a number brother has the same phone number that you do, with only the last digit off by 1.

Hey, we’re number brothers! Your number is 555-555-1234 and mine is 555-555-1233!

number brother by CallMeEOnly August 4, 2019

Brother Number One 

A self absorbed closet case who reveals his ignorance at every turn

Have you seen the definitions suggested by "Brother Number One" he is such a closet case.

Brother Number One by Bubba the Love Sponge April 25, 2004