When a sponsor decides to use an IWRS system to control the IP management at site (receipts, dispensations, returns, destructions), can the IWRS be considered the source data for the IP accountability?

As I understand it, the investigator should have and own records of all IP transactions (for instance, an IP acknowledgement of receipt, IP dispensation form, a destruction certificate, etc). These are the source documents of these transactions. BUT, my question is: which one is the source document for IP accountability? (understanding IP accountability as the inventory, i.e. the result of adding (receipts) and subtracting (administrations, etc) all transactions). IWRS is a place where the inventory is automatically calculated with no errors. The investigator would still own all the source documents of all IP transactions. Except for IP accountability: that piece of information is calculated in IWRS. My question then is: is it also necessary to have a separate IP accountability log (often paper-based) at site where all the transactions AND the calculation of the IP inventory is also performed? Wouldn't that be duplicating information that is already in IWRS?

Thank you!