He changed it to maintain a stage persona when he became famous. Sylvester Stallone discovered him at a club called Dingbats in Chicago's downtown where Tero worked as a bouncer. He became an employee of Stallone's security detail and the name was from Stallone always calling him Mr. T so the name stuck and after he got famous he kept it. I know this because I went to the high school Tero graduated from and ge would come there to give motivational speeches.
Tero Vaara's birth name is Tero Tapani Vaara.
Tero Jartti's birth name is Tero Einar Jartti.
Keijo Korhonen's birth name is Keijo Tero Korhonen.
Lawrence Holofcener's birth name is Lawrence Holofcener.
Lawrence Winters's birth name is Lawrence Whisonant.
Lawrence August's birth name is Lawrence Gustafson.
Josie Lawrence's birth name is Wendy Lawrence.
Judith Lawrence's birth name is Judith A. Lawrence.
Zeddy Lawrence's birth name is Daniel Lawrence.
Baby Lawrence's birth name is Laurence Donald Jackson.
Lawrence Schoenberg's birth name is Lawrence Adam Schoenberg.
Lawrence Bender's birth name is Lawrence Kirk Bender.