I found 2 Dutreuil around the 1900. Both in Champagne and it could be two different dealers or the same one moving from on place to another.
Dureuil at Vitry le Francois near Reims
E.Dutreuil at Epernay.
You may find on the gun after the name of the gundealer the name of the town.
The name of the dealer is without great importance, what really matter is the maker and the quality of the gun, what could be appreciate with pictures of the gun, punchmarks on the flat of the barrels...

g gournet