How to change guid of .net dll

I am currently created c# dll and use it in c++ application. In C# dll, there is one exporting class with unique guid. When I create instance using CoCreateInstance function, only one instance is created in memory. I want to create two or more instances of c#, so I think if I can change guid of c# dll, then c++ application can create two ore more instances using CoCreateInstance.

How can I change guid of deployed dll programmatically? or How can I create two instances in c# dll?