The words overate, overrate sound the same but have different meanings and spellings. Why do overate, overrate sound the same even though they are completely different words?
The answer is simple: overate, overrate are homophones of the English language.
Past tense of overeat.
To overestimate the merits of; rate too highly.
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.