Copy and Paste Multiple Layers (or Group)

Select all layers you want to use > CTRL/Command + Shift + C > Paste in new doc

If you already have some precise selection that you don't want to recreate, make it a quick mask and it will stay in the duplicated image.

Alternatively you can achieve the same thing by just "Save as" with a new name and crop with you current selection. And if you need the previous image just open it. I think this is less hassle if you are going to save the document anyway. "Duplicate" makes sense if you really want to keep the two images open.

Highlight the layers in the layer panel, and then choose Layer > Duplicate layers and drop down the destination to a new document.

D'oh!

Here is one approach:

Right click on the selected layers.

Click on Duplicate Layers..

In Destination box  click on down pointing arrow and select New.  Provide new name & click OK

You have a new document containing the  selected layers.

Paulo