There is nothing weird about typos. Everyone makes them. Some are caused by finger fumbling or typing too fast or slow for your thoughts, but some are caused by that mental dyslexia, where we type what the word sounds like, or a similar situation. Don't worry about it. Just check before you send or print out something, so you can make corrections. I rarely like to bother with the spell checker, as I am a good speller. Normally I just do a visual check with my eye balls, and make my corrections, either as I am typing or after I finish the thing.
I have problems with the online spell checkers anyway. They seem to be British based, and I am American. America and Great Britten are two countries separated by a common language. Some of the words are pronounced differently, and some are spelled differently, so the British spell checker and I are often in cultural disagreement.
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If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau