Cessna172 & Ceyan:
What would be the point of being able to build multiple things like that? Its almost never beneficial to do it as all you are doing is delaying the time before you get any return investment.
The only way something like that could work is if you had a diminishing returns for putting more resources into a specific project. I think MOO3 is supposed to work that way, but the feedback and documentation is so poor that I cant be sure. It looks like both queues use the same type of 'Production Points' so there is no real trade off like that.
A game would need maybe 4 'Build Slots' and they would be optimized for say, 25% of your planetary production. You could favor one slot over another by increasing the percentage of resources going to it, but it would have dimishing returns...so in order to get say, 50% of your resource going to any one slot, it might cost you 75% of your total pool for that turn.
If designed like that, I could see the point in having multiple queues, but as it stands now in SE4, dividing up your points among varying projects is never a good thing to do (much like dividing up your research projects is rarely a benefit). I suppose using the SE4 model, dividing up the points could be useful if you were building larger numbers of small items. Currently, a small ship still takes a turn to build regardless of how many Construction Points you have. If you had multiple 'slots', you could theoretically be building more than one ship at a time. But the times that this would occur would be few and far between.
Anyways, just some food for thought.
Talenn