US1  US2  Product
 4    1      1 
 2    1      1 
 5    1      1 
 4    5      1 
 2    5      1 
 1    5      1 
 3    1      6 
 1    3      6 
 4    2      1 
 1    2      1 
 5    2      1 
 2    4      1 
 1    4      1 
 5    4      1


I want to have something like this

US1  US2  Product
 4    5      1 
 2    5      1 
 1    5      1 
 1    3      6 
 1    2      1 
 2    4      1 
 1    4      1