In Outlook 2016 some users may noticed dual entries in the Room List:
The room list behavior that we see in Outlook is by design. When we use a Room List for a meeting, it is stored in the Most Recently Used entries in the registry. When we create a new meeting, we will see this MRU entry in the top of the Room Lists . The same Room List will be seen again in the drop down which is accessed from the Exchange Server/ Online.
To prevent the duplicate entries seen in the Room List, create the below registry entry with blank data to disable the Most Recently Used Room List in Outlook.
If these entry already exist just empty the values.
After Outlook Restart:
Only single instance of the rooms list now showing! 🙂