Would 3D printing multiple copies at once saves time? I am wondering - of course if the 3D printer's bed big enough - printing multiple copies of the same print could save me significant amount of time in a small production line, excluding minor wastage such as setup time, post-processing time, etc.



e.g. if my foo print takes 10 hours, printing 2x copies at the same time would take 2x times more, increasing linearly or it would be significantly less?
Actually no. It will take slightly more for each addition. You also then have the point of failure, where one gets knocked off and ruins all the prints.
The fastest way to print multiple objects is one at a time. In fact slic3r lets you do just that with their sequential printing feature.
The reason is, the time it takes to lift 0.5mm, travel the few MM over to the next object, lower the 0.5mm back down.. Repeat for inner shells, outer shells, infill.. all add time. Doesn't seem like much till you do it 14,000 times.
In the case of your example, it would be negligible. In more complicated or well spaced prints its another story.
For extra extra fast, look into loss PLA casting...