If you have double system name in your ST03 Workload area like shown below then you can follow my solution steps to eliminate this issue…

This is my situation on my PROD system , there are two system instance names for same system , one is UPPER case other one is just LOWER case…

Correct one ise lower case then we have to delete upper case entry… Detail steps for the process are ;

ST03 (Expert mode)  –> Collector and Performance DB ->  Performance Database ->  Workload Collector Database -> Contents -> Select the data which you want to remove

Press“Delete” button…

Now refresh the tcode and you won’t see wrong enrty under the “Workload” area anymore..