How to copy tags from one note to another in Evernote (PC)
The option for duplicating a note and also copying along the tags is hidden inside the "Notebooks..." menu item. Since I didn't know about it at the time, I had to look for another way to copy the tags from one note to another. I found an easy method...
How to copy a note's tag to another note in Evernote (PC):
Select both notes in the note list.
Right-click and choose Tag Notes...
Check Hide unassigned tags
Press Select All
Press OK
That's it! Now both notes will contain the same exact tags (i.e. a union between both sets of tags).