Hi
I haven't used the IPIVR product standalone and only UCCX but its basically the same.
In HA mode the IVR triggers (CUCM CTI Route Points) register to the Primary CRS server, in failover they will register to the HA server.
Both Primary and HA CRS servers have IVR ports registered to CUCM (CTI Ports), if you have 10 IVR ports in a CMT group then 20 ports will be created on CUCM.
HTH
Andy