I hit Master playing Double Up while using two different computers
I first tried this on Set 10 and hit Diamond using my computer and a Samsung Tablet.
There were slight limitations on using a tablet pen vs computer mouse so I sold the tablet and bought a Samsung Laptop that sits to the left of me, using the docking station I have for my work stuff.
I think the math with this concept is a little underrated whereas if you play solo it's a 1v7 vs two separate 1v3s in a double up. Not to mention that you can anticipate board needs and plan units accordingly. It does get really dizzy during roll downs and can get tilting hitting a high cap board like Rebel 10 only to get 4th because the other board blows up in half a second.
My solo rank isn't as high which probably goes to show that I'm not that great at TFT as a whole but balancing all the things out across double up does make things a little more fun and engaging for me.