accounting to multiple servers

[Nicolás Ciuffolotti]

Hi
Thank you in advance for your help.
I am trying to create 2 servers with freeradius. I have 5 NAS and I
configure the 2 radius in each one but different order, example:
NAS 1 ---> radius A; radius B
NAS 2 ---> radius B; radius A
...
I have the problem with accounting, START and STOP in any radius server.
What is the best configuration so that the files details of both servers
contain the same?
Is there a how to do the configuration?
Thanks for the answers