Arnaud:Are you talking about a 2 stage double hose reg?
The DA Aquamaster is a two stage double hose reg but I don't think the design of a "new" double hose reg was discussed.
In addition to two Aquamasters I also have a single stage double hose Mistral that frankly I prefer over the DA Aquamaster. It would potentially be easier and cheaper to produce a new single stage reg than a two stage reg and performance would not neccesarily be noticeably less at recreational depths.
Like the DA Aquamaster, the Mistral was very common and there are still many of them around so a company making a newly manufactured and updated copy of either one could pick up a lot of additional parts sales supporting existing US divers regs of the same design if there were a large degree of parts commonality.