The thing is, the project I’m working on isn’t max 2 players, it can go up to 8
As far as I know this reusing of the render target won’t happen if you run on several computers (maybe even if you run several standalone instances). So it should only be a problem in testing it when running several instances in the same process. So trying to use two different rendertargets is more just to test that this is actually the reason you get this behavior, cause then you could just ignore it 
I also tried doing that but it seems the behave the same way
In my simple test case it worked (after showing twice the same image when both were rendering to the same rendertarget). Did you swap the rendertarget also in the material (e.g. using two different materials) and the material then in the widget (for testing I created two rendertargets, materials and widgets)?