I can't find any Extron Duet modules from their online database. So is QSC. And so happen they both offer control element now.
Don't think there ever were Extron modules (Duet or NetLinx)
Rob, come on.. In the (Extron) list you linked to, are 78 items, of which 77 are 20 to 13 years old and none of these is a module. very surprising, the 1 remaining is a MVC-121 Duet module from march 2019...
Most Extron Duet modules disappeared when Extron started offering control systems.
Same happened with Kramer Duet modules later on.
Since lots of modules are provided by manufacturers they might decided to withdraw some of them.
It might have also been AMX move.
You never know.