Left = Intake for filter 1, spraybar for filter 2
Right = Intake for filter 2, spray bar for filter 1
That's how I have mine set up - the two filters "cross" over, so they take water from one side of the tank and expel it on the other.
I don't think this is really necessary as the filters will still push the same amount of water through no matter where they are, and the toxins etc will dilute into the same water as long as there is reasonable flow. I spread them out for two reasons:
1) The separate spray bars give a more random flow which covers more of the tank, rather than just a single big circle. This hopefully helps with oxygenation among other things
2) The separate intakes mean that I have two "areas" where small particles, poo and other gunk can be collected, which hopefully gives clearer water.
I don't think either of the above reasons are vital enough to need to move your intake/outputs if it's very inconvenient, but I think they make it worthwhile doing if you have the option. I don't see how it can do any harm, anyway, so even if it does a little good it's worth doing if possible. I Wouldn't worry about it if you can't though, as long as your filtration is adequate for your tank and your water quality is good.
