Sitecore 8.1 Update-2 has introduced a new setting called AllowDuplicateItemNamesOnSameLevel
What is the usaged of this setting ?
In previous versions, Sitecore would not prevent editors from creating items with duplicate names under the same parent.
The item name is used in the path to resolve the Sitecore item (e.g. based on request URL). If multiple items with the same name exist, Sitecore will resolve one at random.
By setting the AllowDuplicateItemNamesOnSameLevel setting to false, Sitecore will prevent creation of items with dublicate names in the same level.