Shortly after taking over Valsuani, Mr. Benatov says he discovered an entirely new set of 74 plaster sculptures by Degas, including a “Little Dancer.” These plasters and the bronzes Mr. Benatov later made from them are the subject of the controversy. Some of the plasters needed repairs and Mr. Benatov, himself an accomplished sculptor, fixed them.

Image Degas’s “Woman Walking in the Street.” Credit... Antoine Mercier/Artco France

Until recently, Mr. Benatov and his artisans had been churning out posthumous Degas bronzes, as well as reproductions of sculptures by Rodin, Modigliani and Dali. Under French law, Mr. Benatov can brand bronzes as “originals,” with the permission of an artist’s heirs or rights holders, or as “reproductions,” once the artist has been dead for 70 years and the bronzes are clearly stamped as such. Since he did not have the authorization of the Degas family to produce originals, he had made reproductions, since it has been more than 70 years since Degas’s death.

Mr. Benatov then cast, and in 1997 sold, 12 bronze “Little Dancers” for around $60,000 each, and another 34 or so a year later. They were all marked “reproduction” under the tutu.

“Otherwise, I wouldn’t have been able to cast them,” he told ArtNews in 2013. “Customs would have come out to the foundry.”

The problem for some Degas scholars is that the plaster sculpture used to make the Valsuani bronzes of the “Little Dancer” is different — the face, the collarbones, the hair, the position of the legs — from the “Little Dancer” that Degas is widely embraced as having made and exhibited.

The authenticity debate has accelerated in recent years, as the foundry had expanded the number of bronzes it produced that were based on the disputed plasters. Increased production was tied to a contract the foundry entered into with Walter Maibaum, a New Jersey art dealer. Mr. Maibaum said he was convinced that the plasters were based on wax sculptures made by Degas, a view that was supported in a published paper by Gregory Hedberg, an art dealer at Hirschl & Adler Gallery in New York, and endorsed by some of the artist’s relatives.