Duplicate files created when unpacking

I've downloaded 2.3 and when I unpack it all files are created twice. Once normally then a second time with a "._" appended to the front of the filename as a partial file. I've tried unpacking in Linux and Windows and ended up with the same results. Did some searching, but haven't been able to turn up anything other than a similar issue reported in the first comment at http://commons.acquia.com/blog/new-dev-release-available-2011-april-18. No solution reported there though. Anyone else encountered this?