People can't copy/backup people's website over the internet or else that would be considered a bot (and a bad one?), wouldn't it?
You don't need a "bot" to download a copy of someone's web site, and there's nothing inherently bad about doing so. For example, I used wget just this morning to download a copy of the HTML-format Subversion book.
The CASPERXP in your user-agent log is almost certainly someone with Casper XP installed. I've never heard of it before, so I don't know what it does with regard to the web, but any application can modify IE's user-agent string. Additionally, it's trivial to do yourself. You can put whatever you want in there.
I can just about guarantee this is nothing to be concerned about.
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