The word Sesteto is misspelled against Sestetto, a noun meaning "A sestet."
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Sestetto has double "tt" is mispronounced as "t"
Remember double 'TT' in between the strings seste & o which should not be misspelled with single 'T'
Wrong Spelling:  seste-t-o 
Correct Spelling:  seste-tt-o 
Find more incorrect spellings of Sestetto to spell right way.