Can't Copy/Paste betweet Two Projects

I want to copy/paste a clip (which includes 2 video and 2 audio tracks) between two projects.  I open Project 1 and copy a clip.  I open Project 2 and paste.  But the paste does not work.  The last copy I did in Project 2 (of a clip that was already in Project 2) is the only thing that pastes, not the clip that I'm bring over from Project 1.  So then I went back to Project 1 and "exported" an xml sequence which contained the clip I wanted to paste into Project 2.  The import into project 2 worked but still I could not copy/paste from the imported sequence to the target sequence in Project 2.  I didn't want to drag he new sequence imported from Project 1 into the the  sequence into Project 2  because I needed to have access to all of the original tracks.  Why doesn't a regular Windows copy/paste not work and what can I do to get the clip from Project 1 to the targeted timeline in Project 2?