The right-hand end of the Tool bar contains the Quick Preferences. These are Vectorworks and…
Vectorworks Tip #018 – Preferences – Allow In-Place Duplication
This preference is one of the Vectorworks preferences. To activate this preference, you have to open the Vectorworks Preferences from the Quick Preferences menu on the Tool bar. It allows you to create duplicates on top of each other, which can be useful in drawings and modeling.