Best Way To Set Up Second External

So I am going to buy another Aqua one aquais 1250 for my 300l tank to run alongside my other one to give the tank a better turnover, but what would be the best ways to set up the intakes and outputs, would this way work best as I will be using duck bills for the outputs once I get the second filter, our would I be better off having the output on the same side as its intake?

Hi, I have this set up on my Rio240 (4ft tank). I have two JBL e901's running - one in each rear corner. The inlet baskets are just in the corner with the basket about 2 inches from the sand and the outlet nozzles are next to them. I've pointed the nozzles so the flow is hitting the middle of the front glass. This seems to swirl the flow back on itself and seems push any detritus back towards the inlet baskets. I don't get many dead spots this way
 
 
Hopefully I've described that well enough - it's similar to your drawing except I keep the outlet nozzles to the same side - saves on the mess of pipes at the back of the tank and it makes them easy to get off when the pipes need to be cleaned

I run two Eheim Pro 350's on my discus tank. If you already have satisfactory surface movement, which I'm going to assume you have given the returning outlet you already employ, I would encourage you to take the second return lower into the tank. My first external I returned using two spray bars joined to give me surface movement over 2/3 of length of the tank. Now, when speaking to a plnt fanatic friend over water movement in the tank he suggested "dead spots", or areas without any flow, should be kept to a minimum. For this reason I took the second return down into the tank, it's 24" deep, in a central position. Then using a tee piece, small prices off tubing and a couple of 45 degree elbows I split this and aimed it sideways and outwards to give better movement lower down. The 2 outlets sit 5" above the substrate.
Hope I've explained that in a way you can understand. I can see how well the distribution is as I also have my inline co2 diffuser running through that returned so I'm able to see the gas moving throughout the tank.