Hi adchealth,
That certainly seems strange – and, honestly, I don’t recall anything similar being reported before now.
I’ve tried to test for conflicts, but this issue happens so randomly, deactivating other plugins or using the default theme doesn’t seem to make any difference in testing.
I appreciate this, yet the very rarity of similar reports suggests there very well may be a conflict at work here (unless someone actually is manually creating them).
You noted this only happens with recurring events from a particular category: can you confirm which category that is? Have there been zero instances of this occurring with other categories, or is the category link more of a suspicion at this point?