Overwrite records with Match key Question

Hello,

I have a question about data loads using this option when loading from infocube - I understand it will overwrite only if all the dimension values match. However what happens if there are two rows in the same cubee with same dimension values. Will it agreegate those two rows and upload that amount? e.g.

Infocube example(Referencefield column wont be loaded to BPC)

ACCOUNT     CATEGORY   TIME    ENTITY      REFERENCEFIELD    Amount

1000                  actual        2013.jan    200N                 1Z                  1200

1000                  actual         2013.jan    200N                 9A                     300

will it upload 1500 or 300?

Tanks