Backup CPU in redundant configuration of PM861 does not come in as 'DUAL'
You will get the same address on both the controllers (primary and backup) once their redundancy is broken. So it is obvious.
I mean, take the stand-alone controllers each (say first Controller 1) and set the IP to 172.16.14.170 and set the back up of the controller from IPConfig tool Settings >> Set Backup IP Addresses (say Controller 2 IP as 172.16.14.171) and subnet mask etc. This IP (171) is for temporary purpose, once you plug into redundancy this IP will disapppera. Please Note: the other controller should not be in the NW.
Repeat the same thing for Controller 2 (keeping Controller1 out of NW), set the IP as 172.16.14.171 and the backup IP as the Controller1.
Now when you are done with IPs, first bring Controller1 to NW and then connect the Controller2 into NW. Then your IP of the redundant controller would take 172.16.14.170.
Do remember, to setup redundant setup out of two individual controllers, they should initially possess two different IPs.
NOTE: For this procedure, you do not have to remove all hardware setup. To use each controller for stand-alone in the redundant setup, you can switch off the other (Trainee) controller which will make your (Primary) controller as stand-alone. Simi;lary, switch off Primary Controller to make Trainee as stand-alone.
Pleas go through the procedure from the manual to setup redundant Controller, it will definitely help.