When a 232-page handwritten score of Mahler’s epic Second Symphony (“Resurrection”) sold for $5.6 million at Sotheby’s in London last month, it shattered a nearly 30-year record for the highest price paid at auction for a musical manuscript.

The Mahler is one of the most valuable post-Renaissance manuscripts of any kind to be sold at auction, fetching more than recent sales of Jack Kerouac’s draft of “On the Road” or Bob Dylan’s lyrics for “Like a Rolling Stone.”

But a less important score that failed to sell that same day has since transfixed the music world. A brief Beethoven work for string quartet went unsold when, before the auction, a scholar publicly questioned the assertion by Sotheby’s, and its experts, that the work was written in Beethoven’s hand — igniting an acrimonious debate in the generally staid, tweedy precincts of musicologists and manuscript dealers.

While it is not uncommon for experts to differ on such matters — Is that painting by the old master or the school of the old master? — the Beethoven episode raised questions about transparency in auctions, even as classical musical manuscripts have become a big international business.