Hi,
Their must be some other characteristic as well because of that you are getting duplicate reocrds otherwise it is not possible to have the data as you are showing.
Normally olap aggregates the data so if you will keep customer and material in rows of query designer and some kf then it should give data in the below format.
Customer 1 ---------Material 1
----------Material 2
--------------Material 3
Hope you understand what i mean to say.
Regards,
AL