Two Admin users are added when creating a new Workspace on a migrated main wiki

Steps to reproduce:

• Create a XEM on 4.5.4. Install workspaces template
• migrate it to 5.2M2 using DW. (also migrate the workspacetemplate) - I clicked continue when I encountered migration conflicts
• after the DW upgrade, create a new workspace. You will see that there are 2 users added as members.

• Admin (XWiki.Admin)
• Administrator (xwiki:XWiki.Admin)

They also are both listed in the Panel on the right side.
Note: This only affect newly created workspaces. The ones which existed priod to the upgrade are OK.