I created two files and there was no way to copy-paste the pages from the two files with each other at the time, I was using the latest version of Axure10
If you want to add a page from one project to another, you can do so via “File > Import from RP File”. Then, select the page that you wish to add.
You can also create a new page in one project, and then in your other project copy and paste all the widgets from the Outline Pane.
It would certainly make things easier if you’re able to copy and paste pages between two open RP projects. I’m not sure what the limitations are behind creating a feature like this but I will go ahead and submit this as a feature request for our product team to review!