KSB1 is giving different result when filtered for one Cost Center or a group of Cost Center

[micheledambrosio]

Hi experts.

I experienced an issue with KSB1.
I need to run this transaction for an identified group of Cost Center.

When I select my group in "Multiple Selection" cost center field I extract the report and I obtained for each Cost Center a value in Report and Transactional Currency.
Anyway, I realized that if I run the same KSB1 for each cost center individually, I obtained a different Report and transactional currency value.

In particular if select the group of cost center I only can see the postings referred to the following business transaction:
RKIU Actual Overhead Assessment
RKL Actual activity allocation.

If I run the cost centers individually, I can also see all the other posting (also COIN business transaction) that refers to that particular cost center.

I am not sure this represent a bug in the transaction KSB1, or this is (and please clarify me why) this is a standard SAP behavior.
Best regards.

Michele