Inscribed on the Liberty Bell is the quotation, "By Order of the Assembly of the Province of Pensylvania for the State House in Philada."
At the time, the spelling of "Pennsylvania" was not universally adopted as having two "N"s in it...In fact, in the original Constitution, the name of the state is also spelled "Pensylvania."
The choice of the quotation was made by Quaker Isaac Norris, speaker of the Assembly.

So! The misspelled word, "Pennsylvania" was actually not misspelled at all! It was just the spelling of the state name at the time :)