Issuing command DB2LIST, only DB2 Subsystems for the active LPAR/System are displayed.
Issuing command DB2LIST XSYS MON, the DB2 Subsystems across all LPAR's that are MONitored by SYSVIEW for DB2 are displayed, and looking at the resulting output, it seems the same DB2 Subsystem it is displayed twice (One Active and another Inactive), but it is not true.
Component : SYSVIEW
This is a normal behavior, when Sysview build the list of DB2's, Sysview gets it from the subsystem table. So if the same DB2 SSID is defined on multiple systems (for redundancy/failover, etc) Sysview will display duplicates in cross-system mode. This is expected, because they are defined in both places.
The status should display ACTIVE on whatever system it happens to be active on. The ACTIVE format ( tabbing Format ACTIVE) will filter to show only those DB2's Subsystems that are active. So, in order to display a list of monitored DB2 Subsystems in cross-system mode, DB2LIST XSYS MON command should be issued.
And, in order to display all DB2 Subsystems, ACTIVE, INACTIVE, MONitored and non-MONitored ones, DB2LIST XSYS command should be issued.