[SR-Users] Kamailio 4.1.(5-3) Dialog Module can't create hash if 2 same Invite comes.

Hello i realize that if two same Invite comes to kamailio sequentially for a call, dialog module cannot create hash data and dont'give any error about it. After get ACK or BYE for this call , it gives warning like 'unable to find dialog for ACK with route param 'f3f1.0524' [7999:16976]' . So i cannot get any data call is hook up from dialog event_route. For prepaid account system , dialog module is weak or i made some mistakes. is there any better solution for accounting for high volume calls. I just need that call is hook up and closed or failed. which module is best option for it? (IMS ,SEAS, RADIUS) Thanks