[Serusers] T1 timer?

Hi, I'm currently facing a situation where UAC A sends an INVITE to UAC B via SER, and SER sends two completely identical INVITEs to UAC B, the second about 50ms after the first one (no second INVITE from UAC A though). Could this be a retransmit? Seems to be a little bit too early (should be 500ms according to the rfc), and I don't think it's a parallel fork because the requests are identical regarding dst-ip/port and the message itself, and there is only one usrloc record. Any other possibilities? And another question: does SER itself retransmit requests when relaying, or is this the responsibility of the calling UAC? If so, how is the T1 timer defined in SER? I only found this one: ./modules/tm/config.h:#define RETR_T1 1 So is T1 defined as one second? Thanks, Andy