Fuel tank hoses

I have ditched my charcoal "green weeny" canister and am in the process of routing all hoses to a catch tank. There is the obvious hose that hooked to the canister which is to vent fumes to the can and not the atmosphere but what does the little hose on the front lower left of the tank do? An overflow? Wouldn't the other vent hose be sufficient as an overflow? It sure leaks fuel when I tip it up with a full tank.
Advice is appreciated!

Yes it's an overflow pipe. it does like it needs a rubber tube on but comes like that as stock.