Create New WorkItem Type In TFS 2015 Issue in Uploading the XML

I want to create new Work Item Type Called "Release" Which is driven from the "Epic" Work Item Type I followed the following steps but I got a primary Key constraint exception in the last step:

1- Renamed the Epic Work Item to release.

2- Export (Download it from the server) the Release XML file.

3- Import (Upload it to the server) as it is with no changes, I got the following exception:

Violation of PRIMARY KEY constraint 'PK__#A4B0716__06C703C1EB09E1A1'. Cannot ins
ert duplicate key in object 'dbo.@tempIdMap'. The duplicate key value is (-20044).