Does this happen outside of the editor?
It may be as simple as 2 clients in the editor sharing the same texture render target.
In a non-editor situation, that shouldn’t happen.
That said, you can just create a texture render target for each client, provided you disable the scene capture updates when its not in use (as TK-Master mentioned).
Else, yeah, performance issues.
To create a new texture render target, you will have to use the CreateTextureRenderTarget2D function that is included with Rama’s Blueprint Function library.