A simple hosted feature layer, collegue's use it offline in collector. Somehow it grew two CreationDate, Creator, EditDate and Editor fields. or at last the aliases are the same, the fieldname shows CreationDate and CreationDate_1 and so on.

This is very annoying when I base the symbology on the CreationDate and at a point in time CreationDate_1 is getting used instead.
Also it is confusing when using for example the definitionquery as that uses the Alias'es:

I would like to know:
- what I did wrong to cause the creation of the extra fields
- How to clean it up so i can get rid of the surplus fields
Thank you for your time,
Bert