Sometimes you can place multiple 3D prints within the same block so long as they do not collide with each other. It looks like they need to have a 2 pixel gap between them but sometimes even with the 2 pixel gap I can't seem to shove a second model into the same block. In addition there seems to be various exceptions to this rule as I have been able to sometimes get as close to a 1 pixel gap between objects placed inside a block. Sorry for the crudeness, but here are some basic diagrams of what I am talking about:
