Duplicate Transaction numbers in Accounts Receivables

We are using a VBCS extension to create and manage transactions. However, we are encountering an error when attempting to create a transaction using a number that already exists in the system. what are our options now should we not duplicate or if we duplicate then what should we change.

Below is the error:

Each line must have a unique combination of INTERFACE_LINE_CONTEXT and INTERFACE_LINE_ATTRIBUTE values for the transaction flexfield. (trx_number*******,customer_trx_id=*******)