When a compare is issued on Source it spawns a process named sp_desvr on Source and a corresponding sp_declt process on Target.
At times there is a need to cancel the compare processes due to a number of reasons.
A "compare config" that takes a lot of time if the config file has too many and/or large tables and the server does not have the resources available to allow such compares to run.
Sometimes the queues may be heavily backlogged and it may be futile to wait for the compare to finish as it will eventually time out.
In all these situations it is better to kill the compare processes on Source and Target.