First of all, you can select the structure, then choose Duplicate from the context menu. This command works only inside the application and can duplicate any object which is displayed on the canvas.
You can move a copy of the selected structure by pressing the
Ctrl button and dragging the selected structure. When you do this, a "+" sign appears beside the cursor. A copy of the selected structure is placed on the canvas when you release the left button, and the original object remains selected, so it can be multiplied several times.
When you click the Copy button, a copy of the selected structure will be created on the clipboard, and the Paste button places the copied structure onto the canvas.
Select what you like to copy, then press the keyboard shortcuts.
*Direct copy-paste between Marvin JS and other applications is available in MRV or MDL Molfile (V2000) format without web services. If web services are available, direct copy-paste between Marvin JS and other applications are possible in every text formats.