Hmmm, if you know the number of the old SysInvPoller job, I wonder if you could delete throuth "jobcli":
Duplicate entries may appears for system RME inventory jobs, when the you try to change the job schedule.
Workaround:
Use the job CLI to delete any unwanted jobs.
1. 
Enter these commands:
cd /opt/CSCOpx/bin
cwjava -cw /opt/CSCOpx com.cisco.nm.cmf.jrm.jobcli delete unwanted_job_id
(where unwanted_job_id is the ID of the job you want to delete.)
2. Then restart the daemons using these commands:
/etc/init.d/dmgtd stop
/etc/init.d/dmgtd start
