The end user navigation shows the "related links" entries twice (or several times) in a workcenter. You would like to avoid double entries like this:
The likely reason is that a workcenter navigation roles has been assigned twice (or several times) to the user.
Remove one of ABAP roles that have been assigned twice (or several times).
Afterwards the user can only see the entries for "Related Links" once.
Regarding ZSAP_SMWORK_SYS_MON role, even though Z roles are created during installation and configuration of Solman, SAP recommedes to keep the Work Center navigational roles unchanaged. They should only be changed if you are customizing them. Therefore, if no customization has been done, keep SAP_SMWORK_SYS_MON role and remove the other. To get a better idea, each role should be opened in PFCG and the description read. Other roles that are recommeded to be kept standard are CRM_UIU roles.