DUPLICATING SMART OBJECTS
When you use the standard shortcut Command-J (PC: Ctrl-J) to duplicate a smart object, changes you make to the smart object will affect both copies. To avoid this, Control-click (PC: Right-click) on the smart object and choose New Smart Object Via Copy. Now the two smart objects can be edited separatelyâ”ideal for making two Camera Raw edits of the same RAW file.
Great info, thank you
This tip leaves out one small but important detail: you have to right-click on the NAME of the Smart Object in the Layers panel, not the Smart Object thumbnail itself.