Don't you think its a weird requirement, why you need two tooltip at a same time ? or you want to show them on different location ?
One way is to Use multiple labels - one for each part.
Otherwise you're going to need to know which characters in the Label the mouse is over - different Font's render differently. That's a can-o-worms if ever there was one.
checkout below link
Editor, DotNetSpider MVM
Microsoft MVP 2014 [ASP.NET/IIS]