HotBot varies results

Completely different results depending on number of results?

[Winooski]

Last week I pay-submitted a page tweaked for a certain keyword phrase.

Today when I search HotBot for the KP, the page appears at #15 for the "Return 10 Results" option...and #4 for any other "Return Results" option (25, 50, and 100). In fact, it seems as though there are two completely separate search results sets for the KP: one for the "10-per-page"s, and the one for the "25-and-up-per-page"s.

Have any of you seen results like this in HotBot? Any theories as to what's going on?