Looking at the processes (in Unix, ps -ef | grep quest_sc_collector, or in Windows, Task Manager under the Processes tab), there seems to be more than one quest_sc_collector per instance.
Are there any circumstances when more than one collector process will appear?
If the collector was configured for use with a firewall, this will put the collector into Call Tunnel architecture. This will cause a secondary collector process to appear on the database host for the configured instance.
(Call Tunnel will also cause a secondary quest_sc_mw process to appear on the middleware host for the configured instance).
This is a design feature of the way Call Tunnel works in firewall setups. There is no workaround, if a firewall is in use, then the additional collector process is required.