Transact SQL :: Insert Unique Values Only Using MERGE

I'm trying to use merge data from a staging table to a production table. There are a lot of duplicate values for serverName and I only want to insert one instance where there are duplicates.

How I can adapt the code I have so far to achieve this?

MERGE tblServer AS TARGET
USING tblTemp AS SOURCE
ON (TARGET.serverName = SOURCE.serverName)

WHEN MATCHED THEN
UPDATE SET TARGET.serverName = SOURCE.serverName, TARGET.serverLocation = SOURCE.serverLocation

WHEN NOT MATCHED BY TARGET THEN
INSERT (serverName, serverLocation)
VALUES (SOURCE.serverName, SOURCE.serverLocation)

WHEN NOT MATCHED BY SOURCE THEN
DELETE;