how separator split traffic

[missyoyo]

Hello:
May I know how separator split traffic, I have try some HTTPS traffic on freebsd and work good.But when I try some tcp random one-way traffic, not works.
./qb-separator -r vmx0 -t vmx1,vmx2
all packet output to vmx1
./qb-separator -r vmx0 -t vmx2,vmx1
all packet output to vmx2
My packet send form diff ip src(but smae mac address) to diff ip dst(but same mac address)

Thank you for you help.