I'd verify the settings in the Organization application to ensure that the "Use Frequency Criteria" checkbox is selected for each of the sites. If so, even with 3 cron task instances, it shouldn't generate the same PM multiple times since the cron task will use frequency. Is the time the PM generates the WOs around the same time (IE 10:00, 10:01, 10:02) or do the times line up with the cron tasks (IE 10:00, 10:05, 10:10)?
Assuming this checkbox isn't unchecked (otherwise this would happen for all PMs), then I would assume it's some sort of data inconsistency causing Maximo to act abnormal. I'd check the PMANCESTOR table to ensure the hierarchy is correct for this PM. We've seen issues during imports where this data is incorrect and causes a variety of issues.
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Steven Shull
Projetech Inc.
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