googlebots!

Looking at the logged in times, it appears you have 4 new googlebots.
Google bot seems to spawn itself more often than other bots. The theory is that it'll index faster, but the trade-off is that a lot of pages get indexed several times on the same day which just increases your bandwidth load.

I "think" one thing that initiates a spawn is if you have a page that links to itself - e.g. a link to your home page from your home page. I "think" that the bot realizes it's in a loop and spawns other bots to follow other links on the page.

As a test once, I submitted a page that had no incoming or outgoing links - just 1 link on the page to itself. The link was full path - www.example.com/testpage.htm. When google finally came to index it, I had 2001 google sessions against the page that day.