Thanks for the tips. I have tried it but without success.
here is what i have tried:
1. Open up usual Dendron workspace;
2. Open a new blank window of VSCode;
3. In the new Blank window I choose Dendron: Switch workspace;
4. I choose the folder of my workspace and click switch;
5. Blank window stays exactly as it was, but my old Dendron window is brought on top.
It looks like that Dendron allows only single instance of a Workspace.. Or maybe I'm doing something wrong?