[Users] ReInvite send twice

Hi !!! I'm using OpenSER 1.0.1 and realized some strange behaviour when SIP UA sends ReInvite Messages. Initial INVITE shown below (this is OK) UA A OpenSER UA B _____________________________________________________________ --------INVITE------------> -----------INVITE------------> <--------200 OK----------- <---------200 OK---------------- ---------ACK-------------> -------------ACK---------------> But when an UA sends a ReINVITE message I realized following behaviour. This happens approximatly every 3rd or 4th ReInvite. UA A OpenSER UA B _____________________________________________________________ --------INVITE------------> -----------INVITE------------> -----------INVITE------------> <--------200 OK----------- <---------200 OK---------------- <--------200 OK----------- <---------200 OK---------------- . . . . Is there any reason for OpenSER sending ReINVTE twice? Any chance to avoid this? Sincerly Stefan