Steps to reproduce:

1. Add Item navigator widget or Host navigator widget
2. Add the following attributes to "Group by" field:
   Host tag value => A
   Host tag value => A
   Host tag value => B
3. Save widget (Unable to save widget - Invalid parameter "Group by": rows must be unique.)
4. Change position of the "Group by" attributes to the following:
   Host tag value => A
   Host tag value => B
   Host tag value => A
5. Save widget

Result:
Widget successfully saved
Expected:
Documentation says "Up to 10 grouping attributes can be specified, and all must be unique.". Not clear behavior. Is this a documentation error, or a misleading message, or both?