I know what you mean. Thats work if is just 2lan behinde load balancing, but I have 2 LINKs, for ex. after 192.168.2.1/30 in next MT I have 192.168.4.1/24, and also after 192.168.3.1/30 in next MT I have 192.168.5.1/24. So first adresses wich is load balanced is just 2adresses, and for 1day can make just 1 connection, so it is same like I predefine wich Isp on wich LAN. There is no Load balancing.
I finde on wiki also LOAD BALANCING OVER PORTS, and thats work nicely to me, but still not perfects.