Because we can't same file name in one folder on windows OS.Seems they are two different files. One has a -2 that makes it different.
Two file are compressed . but one file after upload to a upload center be bigger than one.(similar the image)That's true, but one is bigger than the other. Why not look and compare? Maybe one is compressed and the other isn't?
Yes, no problem.Different versions perhaps.
One could be incomplete. Can you run a full extract on both?