Thanks for the reply. My DB dumps was actually from the same DB. I would assume there will be a lot of duplicates, my guess is the 7zip compression algorithm made the file unique to each other....I don't know but it is good to be aware of this.
I just saw this and maybe it's already too late. But maybe it will help someone else.
The way most compression algorithms are working is that even very small changes in the uncompressed file will cause a "cascade" of differences throughout the compressed file. So even though the uncompressed source files might be 99% identical, the compressed files are totally different.