Not sure how it works in SmartThings - in Z-Wave in general you can use two Dimmers and associate them so that they behave as one.
We did a job where the client had a chandelier that drew a couple of kilowatts. We chased out the wall and whacked about ten dimmers in there!
Lots of people try to get round it by using a relay module, but relays have moving parts and are super prone to welding closed when subject to the inrush current of an LED. The high current causes arcing across the relay contacts and literally welds it closed.
Collingwood lights were telling us their 8W downlights have something like 150A inrush for a matter of microseconds… crazy. Doesn’t bother the dimmer triac but it’s enough to weld relay contacts.
Anyway, don’t fall into the relay trap - gang up dimmers or buy LEDs!