[USR-TC] Platypus, IAS 4.0, Multi-link and double billing

I'm currently running a HiperArc with Microsoft IAS 4.0 Radius for authentication. We're about to move to Boardtown's Platypus billing product. We are trying to bill double-time for multi-link connections, but Platypus is dropping sessions for the following reason. According to the RFC (the Protocol Standard), if a user makes a multi-link connection (ie ISDN), the user should have different Acct-Session-ID's. Apparently the AcctSessionID is assigned by the hardware and NOT the radius server. This means that the HiperArc is not complying with the Radius standard. Anyone know of a fix? thx.