Yes, one UR824 designated as ‘master’ and one as ‘slave’, with adat connections between the two, and then the ‘master’ UR824 connected to the computer via usb.
Before doing this, the ‘slave’ unit has to be set up using the included dspmixFX software to route all its analogue inputs to its adat output, and then shut down (so it remembers this setting), and then connected via adat cable to the ‘master’ unit and you’re good to go.
I’ve said this before on this forum - I think it absolutely beggars belief that Steinberg/Yamaha provide such appalling instructions about how to use multiple units. A quick glance on this forum shows how many of us struggle to get them working - it must be costing them sales.
For what it’s worth, I think these are beautiful units with an exquisite sound.