GetManager Singleton

When I call DynamicModuleManager.GetManager(), is this implemented as a singleton?

For example, if I call this in two different classes/methods, is it returning the same instance?

I ask because I have a repository base class that internally calls GetManager and exposes a get property for accessing the DynamicModuleManager.  Now, I am calling multiple instances of different repositories, inserting records, and I would like to know at that point if it is safe to call SaveChanges once for all repositories, or if I will have to call it for each repository.

So, no one can confirm if this is a singleton?  Ive since worked out my code another way, but it would still be nice to know beyond my own assumption that it likely might be.