Oculus RIft DK1 and DK2 compatability

For a project I need to make a multiplayer game using Unity and the Oculus rift. My project works fine with the DK2 but it turns out the second rift is a DK1 and it won’t work with Unity. I was thinking the best way forward would be to use an older version of the Oculus Runtime and Unity. Does anyone know what versions of Unity and the Runtime I need to have both the DK1 and DK2 work with Unity?