"keyword1 more:keyword2"

What does this mean?

[europeforvisitors]

In the last few months, my server logs have shown significant number of referrals for several phrases like:

keyword1 more:keyword2
keyword3 more:keyword4

or, to widgetize it:

cityname more:widgeting

This is something I don't recall having seen until fairly recently. Can anyone tell me what it means? (I don't imagine that many people are actually searching on "cityname more:widgeting.")