Click this button to duplicate all the selected bones. You must use this button to duplicate armatures and be able to (auto-)rig them later, so that Duik can handle some hidden properties for you (like updating an identifier used to recognize limbs and armatures during the rig process).
If you duplicate bones with After Effects (
[Ctrl] + [D]), Duik won’t be able to correctly rig them later.
Using this tool also keeps your timeline tidy as Duik will keep armatures grouped together, to the contrary of After Effects.
Duplicating with After Effects is a mess.
Duplicating with Duik keeps the timeline tidy.