Posted by Coriwright on Jul 06, 2012; 8:06pm
URL: https://forum.librecad.org/Copying-from-one-document-to-another-one-tp5550173p5706853.html

You can copy from one document to another as long as they are both in the same instance of LibreCad.

Sooo...

Open up one file in LibreCAD
Then use the File-->Open Menu item (or the open folder shortcut) to open the 2nd file

Now you can copy and paste between the two.  If the other file is in a new instance, then you cannot copy and paste.