I understand your confusion. These are the exact words I received:
This letter does not replace the permanent resident card; you are still required to submit the documentation to obtain your permanent resident card. If you have Confirmation of Permanent Residence (CoPR) documents in-hand, please send both of them (signed) with one photo that meets our photo specifications to the address listed above. Please ensure that you write your unique client identifier (UCI) and name on the back of the photo. Please write your current address on the Address section of your CoPR documents (both copies).
It varies slightly from what you have. For information I sent both CoPR documents in-hand signed, making sure the details requested on the back of the photo supplied were there. There was no specific "Address Section" in my case so I wrote my current address on the CoPRs in a suitable place - hopefully this shouldn't invalidate these documents.
In your case I see no logical reason why you should send any document to them unsigned. I imagine you will be sent back your copy with their signatures filled in together with your PR card. That makes sense since some here are saying that you need a CoPR for future applications such as the Citizenship application.
