Return visitors stats question

Hi,

We are actually using the previous incarnation of Piwik (PhpMyVisites) and have a question about how the “Returning visitors” are calculated.

Here’s what we’ve gone through recently:

1.We originally had a site listed on PhpMyVisites that was hosted in our offices and was busy gathering visitor stats.
2.We then moved our site hosting to a co-location center away from our offices in November 2008.
3.At this point I created a new site listing on PhpMyVisites at the start of December 2008 to begin tracking this from scratch (the url was the same - just a different hosting location)
4.In our December stats, we have 50 returning visitors. We don’t see how though as it was a new site listing and wasn’t listed for the previous month.

So… is it telling us we have 50 returning visitors from November (when we didn’t have the new site listed so that would be odd)… or is it telling us we had 50 visitors who came to the site and then also returned ‘during’ December?

I look forward to your replies.

Thanks

Has no-one got any ideas on this then?