you have to create a new ephone-dn, at the end your configuration should be like the following (second line 9331)
voice-port 0/0/0
connection plar 9331
ephone-dn 1 dual-line
number 9332
ephone-dn 2 dual-line
number 9331
ephone 1
mac-address xxxx.xxxx.xxxx
type CIPC
button 1:1 2:2
Hussam