RTNFA Multiple interfaces to capture?

Hi, have just setup netflow on an 857 running 12.4(15)T9 and am confused with the number of interfaces im able to capture. I've enabling net flow individually on both the dialer and the internal vlan1 interfaces and both show two interfaces (Interface 12 & 16 in this instance) to capture from in RTNFA.

Config below

ip flow-export source Vlan1
ip flow-export version 5
ip flow-export destination 2055

interface Vlan1
 ip address 192.168.xxx.xxx
 ip access-group xxx in
 ip flow ingress
 ip flow egress
 ip nat inside
 ip virtual-reassembly
 ip route-cache flow

When capturing one interface appear to show outgoing and the other incoming but i cant view a capture of both together? Is this simply a limitation of the free tool?