Single visitor is counted multiple times

since yesterday Piwik is behaving oddly. At least twice I had the case that a single user viewing multiple pages (one after another) was counted as multiple visitors instead. That looks good in the user stats style_emoticons/<#EMO_DIR#>/wink.gif but screws the results. I checked in the visitor log and it seems the mistake originates from the same IP address (it is from a bank in Azerbaijan …). Does anybody have an idea what causes this problem? How can it be solved? And is there a safe way to manually delete the entries from the database?
Thanks a lot.

Are you sure it’s not more than one person sharing the same IP? Maybe one person saw your site and told a friend/coworker about it.

yes, I am pretty sure about that. The user had searched for a term on goolge and then viewed several different pages one after the other in intervals of a few seconds (i.e. normal behaviour). Settings of OS, browser, screen resolution, etc. are identical (Win 2000; Firefox 3.5; normal; 1280x1024;pdf, flash, java, windowsmedia). For most entries the referrer URL is the page (on my domain) he had visited last.
Any thoughts?