You can clone with
I want to use the following command to open two graphical vim windows with two splits each:
mvim -O . foo.h foo.c; mvim -O . bar.h bar.c;
However, when I do so, the second mvim to open bugs out with this error: http://ell.io/KKPG
On second glance, this might not be specific to NERDTree. That command seems to open two isntances of MacVim, though I’m not sure why.