Google (1997)
Alternative name: BackRub
It is very probable that BackRub doesn't mean anything to you. But it was the first name of the search engine that would eventually become Google. However in 1997, when the brands and names were going to be registered, Larry Page and Sergey Brin opted to go with now well-known Google.
Later, in 2015, parent company Google Inc became Alphabet Inc, marking its second name change, with a similar move that was made by Facebook Inc with Meta in 2021.
Sony (1958)
Alternative name: Tokyo Tsushin Kogyo, Totsuko
In 1946, Akio Morita and Masaru Ibuka founded Sony with the name Tokyo Tsushin Kogyo. Even though they later started to use casually the acronym "Totsuko", it was very difficult word to pronounce especially for Americans.
In 1958, they renamed it as Sony, a combination of the Latin word "sonus", meaning sounds, and "sonny boys", which is an American slang borrowed by Japanese people to refer to an "intelligent young person".