[Serusers] SER is not matching ACK Messages

[Alejandro Olchik]

I'm experiencing some strange behaviour on SER.

When an enpoint sends an INVITE and after some 180 Ringing
messages cancels the call, SER forwards the CANCEL message to the
destination  and replies with a 200 Cancelling message.
(this seems to be OK up to this point)

20ms after the Cancelling message was sent,  SER sends a 487
Request cancelled message twice with 80ms of difference
(any ide of why this is done?)