Issue with simultaneous screen sharing & live streaming

[streamer]

1. We are doing republishing as RTMP, can we steam webcam feed + screens at the same time ?

2. We can do individually and its working, but share screen along with webcam stream is throwing this error "used stream , stream already in use, and streams getting terminated"

 

[Max]

Good day.

1. We are doing republishing as RTMP, can we steam webcam feed + screens at the same time ?

Yes. Please see the example Video Chat and Screensharing.
Note that in this case 2 streams must be published, one for webcam and one for screen.

2. We can do individually and its working, but share screen along with webcam stream is throwing this error "used stream , stream already in use, and streams getting terminated"

As mentioned above, there should be two streams published simultaneously, named for example webcam and desktop. So you should republish both streams separately.
Another option is to use stream mixer. For example, you should publish webcam stream as webcam#mixer and desktop stream as desktop#mixer. In this case, the mixer output stream mixer should be republished as RTMP.
Note that mixer requires at least 2 CPU cores per one mixer, so the server should be powerful enough.
Please read details about stream mixer here.