Query to combine each duplicate found entry
Since performance is obviously not going to be a high priority here (all this XML PATH concatenation is quite expensive), and since the only real problem with the output is that you have duplicates, try changing this:

SELECT [USER],  
    STUFF(b.[licenseDup],1,1,'')    ...
  FROM
    (SELECT DISTINCT a.* FROM [FEBCardb].[dbo].[sheet1$] ...


To this:

SELECT DISTINCT [USER],  
    STUFF(b.[licenseDup],1,1,'')    ...
  FROM
    (SELECT a.* FROM [FEBCardb].[dbo].[sheet1$] ...