Questions about sharing desktops

[Liu]

hello:
I am a java programmer and have a question about sharing remote desktops.
How to implement a shared desktop at the code level?I simulated two users using 
the same GuacamoleTunnel to achieve shared desktop??but the result is that 
neither user can connect to the remote desktop.I would like to know if it is 
possible to use the same tunnel to implement shared desktops. If not, how is 
the shared desktop implemented?