Combine column value from multiple table

Hello duycao 

You can create a calcualted table that give you the unique list from both tables like so.

Combined Table = 
DISTINCT(
    UNION(
        DISTINCT(Table1[Customer Name]),
        DISTINCT(Table2[Customer Name])
    )
)

You can continue to add the additional source tables in this one calculation.

Combined Table = 
DISTINCT(
    UNION(
        DISTINCT(Table1[Customer Name]),
        DISTINCT(Table2[Customer Name]),
        DISTINCT(Table3[Customer Name]),
        DISTINCT(Table4[Customer Name]),
        DISTINCT(Table5[Customer Name])
    )
)