In Modo, using the Duplicate command creates a single copy of any item (or duplicates of multiple items if you select more than one item). You can invoke the command in the Duplicate sub-tab of the modeling tools panel or by choosing Item > Duplicate. (To duplicate geometry components, such as points or polygons, it is better to use the Copy and Paste commands.) There are no dialogs or options with the Duplicate command. Select the item and invoke the command. Then Modo creates an additional item and adds it to the Item List. When Modo creates the item, it automatically appends a number to the end of the duplicated item's name to avoid naming conflicts. You can adjust the protocol for the naming in the Modo system Preferences. To rename the item, simply right-click the new item layer and choose Rename.
The Duplicate Hierarchy command is similar to the Duplicate command; however, it also duplicates all descending hierarchy items as well to retain the parent/child relationships of the originating item. There are no dialogs or options. Select the item and invoke the command, and Modo creates the additional items and adds them to the Item List.
Invoking the Duplicate Options command presents a dialog with several options for duplicating items. To invoke this command, choose Item > Duplicate Options. If you select the Instance checkbox, Modo generates an instanced clone of the original item(s). If you select the Hierarchy checkbox, Modo duplicates the descending hierarchical chain of the selected item to retain the parent/child relationships. If you select the Modifiers checkbox, Modo properly duplicates any modifiers associated with the selected item(s).
If you invoke the Instance command (Item > Instance), Modo creates a single instance (a copy) of the selected item(s). Instances are different from duplicated geometry in that they reference the originating item. Because Modo transmits any component modifications made to a source item automatically to all descendants, they do not require additional scene memory and, therefore, can be duplicated many times over with little to no performance effect on the scene. You can recognize instanced items in the 3D Viewports by their distinct pink wireframe representations and can only modify them by using an Item transform. If you wish to modify an individual instance, convert it to a standard Mesh Item by right-clicking the instanced item's name in the Item List and choosing Change Type > Mesh.