Pivot table keeps dupping to another linked pivot table
 

I have two pivot tables, they use same source of data so i make pivot table B
link with pivot table A, not only the save size but also they can be
refreshed together. It usually works well but today don't know why pivot
table B becomes a "mirror" of pivot table A: When i change one the another
one changes in the same way, so I cannot make them to analyse with different
content, why?

Did I setup something by accident or what?