The words bit, bitt sound the same but have different meanings and spellings. Why do bit, bitt sound the same even though they are completely different words?
The answer is simple: bit, bitt are homophones of the English language.
A small portion, degree, or amount: a bit of lint; a bit of luck.
A brief amount of time; a moment: Wait a bit.
A short scene or episode in a theatrical performance.
A bit part.
A vertical post, usually one of a pair, set on the deck of a ship and used to secure ropes or cables.
To wind (a cable) around a bitt.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.