The entry named 'http.XXXXX' is the actual directory in which the Analog stats files are stored.
The entry labelled 'http' is simply a symbolic link which points to the first directory ('http.XXXXX').
I imagine that this is the case so that you can simply refer to the log directories with the 'http' directory name in the path, instead of knowing the full name of actual log directory which, given that we have a static symlink, probably implies that the actual directory name ('http.XXXXX') has the potential to change, should your site migrate from one server to another at some future point.
The data only exists in one place, you simply have two paths to get to the same files.
I was writing a cheesy-little PHP script today to go through the Analog bandwidth logs so that I could display the monthly and billing-cycle traffic totals for one of my subdomains, so I know it's a whole lot easier to reference the symlink than the actual directory name.