Get Distinct on only one column

I am using this below query to generate this below result set. I want to display only one record as blank, it should not be duplicate records.

SELECT [MDMTerminalID],  ISNULL([TerminalAlias], 'BLANK')  , [RegionID] FROM [dbo].[Terminal]
Union
select -1,'All', (select top 1 areaid from area where name = 'Other')