Unfortunately showing multiple Tooltips simultaneously on the same page is not a supported feature of the RadTooltip control. We will consider this for implementation.
In that respect I would ask you to create a new feature request for supporting multiple tooltips on the page describing your scenario and specific features that you may need. This way others could join the discussion and thus creating requirements that are most in harmony with the end result that you would expect. Here is the link to the Telerik UI for ASP.NET AJAX feedback portal - http://feedback.telerik.com/Project/108/
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.