Here’s a Chris Strub recommendation from the Zwift forums archive: 2 Rider Setup
I can run two split screens with no issues. Sometimes I ride and my wife runs. She likes trainer road for riding. Yawn!.
Anyway. If you have a good enough PC with graphics card. Here is what you do.
Copy the entire Zwift folder onto your desktop. Go into the newly save folder. Rename the zwift icon to Zwift2.exe. or something which makes it different than normal icon. Place this new icon beside the other one on the desktop.
1st user log in to zwift. Go into settings and change to windowed mode. Log out.
1st user log into zwift. Pair ups sensors. Depending on side of room, drag the screen to shrink it so it only takes up half your TV.
2nd user, log in using Zwift 2 icon. Drag that screen the other way so it only uses half the screen. pair up sensors. Play with screen size to even them both out.
Continue riding zwift as you normally would.
Things to have: Two Zwift accounts. Two Ant + sensors and extension cables. Powered USB hub is a good idea when extending sensors with cables.
It’s fairly simple. I do use s 55" screen. See example below. I am in both screens.