Copy named formula's from one doc to another

Hi, I am rather a newb, but I can’t seem to figure out something simple.
I created a page that holds named formula’s for issues that are recurring (like reformatting dates to my own locale). Since I name those formula’s they are very easy to use in all pages of a doc.

Now I would just like to copy that page to another doc, but reading an existing thread that option does not seem to be there yet. Then the only possibility I see is just to copy the content of that custom formula’s page and paste it in a page of another doc. The only issue I have in that case is that the formula names get a suffix 2… So the formula names seem to change. I thought that named formula’s can only be used within the same doc, so I don’t understand why the suffix appears.

Does anyone know a work around?