I can kinda see this happening but I'm wondering how you zipped it up all the way from the inside to begin with? I would think you could have unzipped it the same way right?
I had to use my fingernails to move the zipper all the way against the 2nd zipper, but the fabric on the door side of the tent was really tight, and the zippers stuck at the top. I tried moving them with the metal, but no go.
There were some minor light leaks on some of the stitching, but otherwise it was pitch black until I opened the vent hole. The door zipper seam leaked light, so I was able to see where to try and cut.
I vote for Double-Sided Zippers!!