Avoid duplicate staged dunning letters when account is used across multiple OU's

Hi

Collections 12.1.3.

We are using staged dunning plans at the "Account" level. The accounts are used against multiple OU's. We would like to send one dunning letters for all delinquent transactions across all OU's for a particular entity at each stage. When we run the IEX: Send Dunnings for Delinquent Customers for the first OU it creates the dunning with all the delinquent transactions as we require. However if the account has deliquencies in multiple OU's the same dunning letter will be sent  when the subsequent IEX: Send Dunnings for Delinquent Customers concurrent requests are run  for the other OU's.