Several VisualCron clients can be connected to the same VisualCron server, typically one client both has the VisualCron client application and the VisualCron tray client connected to the same server. See Server -> Client connections for a list of clients that are connected to the currently selected server.
The VisualCron client can also switch its server connection in the Server/Username "track" in the top of the Server/Job/Task grid.