I did copy both files. When I copy them both again it asks to replace both, which I accept. Same error.
I had the same thing happen. I got it fixed, but not 100% sure how/why. Here is what I discovered... When I unzipped the file it resulted in two files and a subdirectory which contained another copy of one of the files. I added both files and the subdirectory via iTunes file menu and then it worked. That was my experience in any case.
I did copy both files. When I copy them both again it asks to replace both, which I accept. Same error.