When you change RadGrid's page, its items are recreated along with any controls inside. This means any previously selected radio buttons should re-initialize in their default unchecked state. RadGrid's selection is page-based when you enable paging, so neither selected indexes nor checked radio buttons should be persisted in any previous page when you navigate away.
Can you send us some sample code and describe what exactly is your scenario, so that we can identify why you are getting radio buttons in previous pages checked?
the Telerik team