Shift + D not creating new object In the below image the three highlighted borders, except for the vertical one on the right were creating using Shift + D:



The component "Cube" was the initial mold for the highrise; Cube.001 was added in separately and scaled 
into the vertical left frame. The top and bottom frames are copies of it that were rotated and scaled to fit the top and bottom borders. Why aren't they each a separate component (e.g. Cube.002, Cube.003)? Shift + D is suppose to make an actual separate copy. In edit mode, they are three separate objects:



In this video 

https://youtu.be/emT-CL957HE?list=RDCMUCOKHwx1VCdgnxwbjyb9Iu1g&amp;t=646

it's its own separate object; when I click the vertical cube, all frames (top and bottom are selected).
You need to be in object mode to duplicate an object (as a separate object). In edit mode it will duplicate your selection IN the same object.