You can't have multiple rules for the same traffic. There are iptables rules for the MITM transparent proxying of traffic. What you need to do is create a prerouting rule that will tee or copy the traffic..
iptables -t mangle -A PREROUTING -p tcp --dport 80 -j TEE --gateway BURP_IP:PORT
http://linuxcommand.org/man_pages/iptables8.html
ROUTE
This is used to explicitly override the core network stack’s routing
decision. mangle table.
--oif ifname
Route the packet through ‘ifname’ network interface
--iif ifname
Change the packet’s incoming interface to ‘ifname’
--gw IP_address
Route the packet via this gateway
--continue
Behave like a non-terminating target and continue traversing the
rules. Not valid in combination with ‘--iif’ or ‘--tee’
--tee Make a copy of the packet, and route that copy to the given des-
tination. For the original, uncopied packet, behave like a non-
terminating target and continue traversing the rules. Not valid
in combination with ‘--iif’ or ‘--continue’