Fail on incoming call from same provider

I have 2 sip connection subscriber to the same provider. There is no problem in outgoing call. However one of the incoming call route always drop. And I have dumped and checked that the incoming connection always set to first reg number only.

Is there anyway separate the peer connection or it is a bug?

Case
Phone number AAAAAAAA
Phone number BBBBBBBB

dial-in AAAAAAAA
no problem
Executing Set(“SIP/AAAAAAAAhk-09e4f958”, “FROM_DID=BBBBBBBB”) in new stack…

dial-in BBBBBBBB
drop call
Executing Set(“SIP/AAAAAAAAhk-09e85269”, “FROM_DID=BBBBBBBB”) in new stack…

My setting in sip.conf
register=AAAAAAAA:upwd@proxy:5060/AAAAAAAA
register=BBBBBBBB:epwd@proxy:5060/BBBBBBBB

[hkbn]
username=AAAAAAAA
user=AAAAAAAA
type=peer
secret=upwd
qualify=yes
port=5060
nat=yes
insecure=very
host=proxy
fromuser=AAAAAAAA
fromdomain=proxy
dtmfmode=inband
disallow=all
context=from-pstn
canreinvite=no
authname=AAAAAAAA
allow=alaw

[hkbn]
username=BBBBBBBB
user=BBBBBBBB
type=peer
secret=epwd
qualify=yes
port=5060
nat=yes
insecure=very
host=proxy
fromuser=BBBBBBBB
fromdomain=proxy
dtmfmode=inband
disallow=all
context=from-pstn
canreinvite=no
authname=BBBBBBBB
allow=alaw