As reported in KB article 234876:
ErrorMessages = (2018-08-28 22:02:45.603) Executed on: syncserver_eu11corp
[2262003] Error executing process task "MaintainOtherSid".
[System.ArgumentException] An item with the same key has already been added.
at StdioProcessor.StdioProcessor._Execute(Job job)
at VI.Projector.ADS.JobComponent.Tasks.MaintainOtherSid.Execute()
---- Start of Inner Exception ----
at VI.Projector.ADS.JobComponent.Tasks.MaintainOtherSid.Execute()
at VI.Projector.ADS.JobComponent.Tasks.MaintainOtherSid._Execute()
at VI.Projector.ADS.JobComponent.Tasks.MaintainOtherSid._LoadKnownSids()
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)