Subline billing Streams being duplicated when the contract opend for update.

Hi,

We have several contracts wher the subline billing streams get duplicate lines automatically and the QA check fails with errors. We cannot delete the duplictae lines manually from the front end but have to run a data fix to delete the billing stream lines from the back end. This cannot be reproduced at will but does happen every now and then. First the duplicate billing stream lines are created with zero pricing then when the contract is opened for update and any changes made at the subline pricing, the duplicated billing stream gets activated and the QA check fails with