Yes you can have two window of the same file in Krita. The steps to achieve what you want is:

1. Go to Window > New Window this will open a second window of Krita's interface.
2. Move the newly opened window to your other monitor, then in the new window go to Window > New View and choose the file that you want in the list.

Yes you can have two windows of the same file in Krita. 
The steps to achieve what you want is:

1. Go to Window → New Window. This will open a second window of Krita's interface.
2. Move the newly opened window to your other monitor, then in the new window go to
   Window → New View and choose the file that you want in the list.