F.07 customer balance carry forward doubts

Hi folks,

i have some concerns about T-code F.07.

1. Can we run this Tcode more than one time for a particular customer account for the same fiscal year? If it's allowed what will happen?

2. For the record in KNC1 table, if we run the F.07 twice, what will happen? will the system created two records, or the second run will update the first run. eg. the first carry forward have the amount 400. and after carry forward this is another invoice posted wit amount 100 with the posting day in the previous fiscal year, so will this 100 carry forward automaticly? or need to run the balance carry forward again for this customer ? and what's the records looks like in table KNC1 for these three phase?

thanks in advance