We are currently facing an issue due to the way our AD is setup where we have two OUs that basically contain duplicate data of each other, plus a third OU that contains users external to the organization. We are trying to find some way for SharePoint to only use two of those three OUs, but so far we have not been able to find a solution and have had to include all three OUs. This causes users to see duplicate names in people pickers, and one of the two names is not valid and the user really has no way to tell the difference.
Is there any known ways to tell SharePoint which OUs it should be including and which it should be excluding?