It is possible to have the same file in more than one (1) folder?
Something like symlinks or hard links in Linux.
Yes. Locate the file in its original folder, and select it.
Now press Shift+Z.
From the folder select window that opens, navigate to the folder where you would like to add the file.
Now, the file is available in both its original and the newly selected folder.
Be aware, that if you navigate to the new folder, and press Delete on the file there, it will be deleted from both locations (or, more precisely, it will be moved to the Trash can).
If you just want to remove it from one of the folders without deleting it from everywhere, select the file and click the (i) icon. The sidebar that appears lists all the file's folders, and lets you remove them individually.