Unless you have a powerfull pc this will take a lot of your system.
(2x obs = 2x encoding) But it can be done by adding -multi in the taget path in the shortcut properties.
But if you have a 2nd pc around you can install nginx+ rtmp server on that.
Capture the game once on your pc send it trough your network to the server and the server forwards it to several streams at the same time. Takes some time to setup but there are guides for that available on the forum.