I'm not sure I agree with that. I thought Dunning-Kruger requires the person to NOT know they are in over their head or misunderstanding their level of knowledge. "Fake it 'til you make it" is acknowledgement and awareness by the person they are not knowledgeable/competent, but will pretend they are until they acquire the knowledge they lack. The big difference is the awareness.
Dunning-Kruger = not having the awareness
"Fake it 'til you make it" = being very the aware, but choosing to go forward anyway