I need to add more Illustrator objects but the new objects are inside the same file as the old objects. How do I add the new objects without getting extra copies of all the old objects

Inside Illustrator, put the new objects on their own layer, then turn off the visibility eyeball on all of the other layers and save the file. The Invigorator will ignore all layers with their visibility switch turned OFF. When you open the file only the Illustrator paths on the visible layers will be turned into 3D objects. (NOTE: you do not have to have the Open By Layers option enabled to get this to work.)