Yes - I think I know the difference
having owned both
The Uno 1116cc and 1301cc after 1987-ish came with a DMTE carburettor. The 'E' stands for 'Emissions' (in effect) since there is a fuel-cutoff valve incorporated but also an idle-up device (on later 1301cc versions) that permits the manual choke to be pushed in sooner. This idle-up device is a square diaphragm-thing that pulls on the throttle at the back of the carb.
Another difference is that the idle system has a large thumbscrew on the older DMTR, which is a bypass adjustment. The DMTE just has the usual screw that pushes the throttle open.
Practically though, there are jetting and venturi differences. Assuming that you have a 1301cc-version of the carb, here they are:
___________________DMTR______DMTE
Barrel sizes_________32/32______30/32
Venturi sizes________22/22______19/23
Primary Idle jet______0.50_______0.45
Primary Main jet_____1.05_______0.90
Primary Air Corrector_1.95_______2.20
Secondary Idle jet___0.70_______0.70
Secondary Main jet__1.15_______0.97
Secondary Air C'tor__1.90_______1.75
Obviously there are other differences but these are the main ones... and as you can see, the DMTE gives you less fuel and more air, basically. It's designed for the 'soft' cam of the Uno that doesn't allow the engine to develop as much power at high revs, but gives reasonable torque (a little more than the 128) at lower revs.
Hope this helps!
Cheers,
-Alex