Unstable Asterisk

Hello every body,

I have a weird problem; I have two asterisk connected together and with each asterisk i connected an xlite softphone, xlite1 xith number 1111 and xlite2 with number 2222. when I call xlite2 from xlite1 there is a chance that the xlite2 will ring, that 's mean that if I am lucky the xlite2 will ring (seriously the phone ring by coincidence).

Also there is another thing; the xlite1 user is test1 registered in and the xlite2 user is test2 registered in, when I look to the log of asterisk CLI this what i see:

Registered SIP ‘test1’ at port 5060 expires 120
then after a while
Registered SIP ‘test1’ at port 5060 expires 120

So is that normal ? I have register as normal :
register => test1:test1@ in server2 sip.conf
register => test2:test2@ in server1 sip.conf

I really appreciate any help.
Thanks in advance.

xlite1 and server are trying to register to as same user.
You cant have predictable behaviour this way.