Hi,
The main property of the infocube is summation, The cube doesn't overwrites the data.It just adds the data.
So you are getting the muliple records with the summation property of infocube.
In the first load there are 12 records and in the second load 12 records,finally the cube consists of totally 24 records.that means it just add the records.
Hope you got it
Regards
Padmaja