WINS registration for DHCP clients

I have 2 subnets connect vs T1. Each subnet has its own DHCP server also acting as WINS and DNS server.

Each DHCP server is configure with only one scope that assign WINS and DNS server in the same subnet.

for some reason, some clients at subnetA would get their IP address for local DHCP server but register their name in remote WINS server at subnetB. and some clients don’t

why is this happening? and how to make sure clients register WINS using local WINS server?

Appreciate the help!