Here is an example how to configure two contexts. Both use a policy-group ADMIN, but both with different settings:
webvpn context SPLIT16
!
policy group ADMIN
svc split include 10.255.0.0 255.255.0.0
virtual-template 2
default-group-policy ADMIN
aaa authentication list VPN
gateway VPN domain split16
inservice
!
webvpn context SPLIT24
!
policy group ADMIN
svc split include 10.255.255.0 255.255.255.0
virtual-template 2
default-group-policy ADMIN
aaa authentication list VPN
gateway VPN domain split24
In AnyConnect you need to use the fqdn "vpn.example.net/split16" or "vpn.example.com/split24" to select the different contexts (these are the commands "gateway VPN domain NAME").