There were a number of companies that made them under their own names or for some other distributors. Iver Johnson at least had a better safety device but not better parts fitting or trigger pulls. H&R sold a huge amount under their own name. Marlin Firearms Copied the D A Revolvers as well as the earlier tip up revolvers. There were some called Secret Service that I believe were made by Hopkins & Allen. Andrew Fryberg, who invented the Hammer The Hammer Safety for Iver Johnson, manufactured Copies of the S&W D A revolvers. There were many others right up until WW2 During the last quarter of the 19th century there were numerous copies of all of S&W small revolvers by a huge number of manufacturers and supply houses.
Best source for information that I have are the Flayderman's Guide and the book SUICIDE SPECIALS by Donald Webster jr.
This solid frame D A manufactured by T E Ryan Of Norwich CT is actually stamped the "LATEST MODEL S&W"