Multiple sip with same provider

I have multiple sip accounts with the same provider.
I need the line auth = for both accounts in sip.conf with the same authuser and realm but whit a different secret.

If i use one account all works well, when i add the second account the registration fail.

with is the right way to use te both accounts?

we use asterisk 1.4.22 whith the asterisg-gui 2