It is one of the most popular of classical works--available in dozens of recorded versions -- but "Albinoni's Adagio" was not written by Albinoni.
The theme in Brahms' Variations on a Theme of Joseph Haydn is most likely not by Haydn, and the famous Toccata and Fugue in D may or may not be Bach's.
Stravinsky based a ballet on themes of 18th century composer Giovanni Pergolesi-but as it turns out, half of them were by other composers.
And the enthralling high notes of Allegri's legendary Miserere apparently are the result of an error by a 19th century copyist.
In this hour, these and other 'loose' connections of the classical music repertoire--some the result of carelessness, others due to honest mistakes-and a few cases of outright fabrication.