dhcp3 round-robin multiple subnets

Hi,

I have two dsl uplinks to my provider and two different public
/25-networks routed over them. I would like to do a kind of round-robin
via dhcp to assign public ips to my internal clients equal on both
networks. I already have a working dhcp-setup with isc dhcp3 which works
like this:

....

default-lease-time 600;
max-lease-time 600;

shared-network "internal" {

subnet 87.1.1.0 netmask 255.255.255.128 { pool { range 87.1.1.1; option
routers 87.1.1.126; option domain-name-servers 192.168.9.254; } }
subnet 87.2.2.0 netmask 255.255.255.128 { pool { range 87.2.2.1; option
routers 87.2.2.126; option domain-name-servers 192.168.9.254; } }
subnet 87.1.1.0 netmask 255.255.255.128 { pool { range 87.1.1.2; option
routers 87.1.1.126; option domain-name-servers 192.168.9.254; } }
subnet 87.2.2.0 netmask 255.255.255.128 { pool { range 87.2.2.2; option
routers 87.2.2.126; option domain-name-servers 192.168.9.254; } }
subnet 87.1.1.0 netmask 255.255.255.128 { pool { range 87.1.1.3; option
routers 87.1.1.126; option domain-name-servers 192.168.9.254; } }
subnet 87.2.2.0 netmask 255.255.255.128 { pool { range 87.2.2.3; option
....
}

....

isn't there a easier way to do this with dhcp?

thanks
oli