I have two different namespaces, with lots of classes with the same name. I believe some code will make it easier to understand:
namespace Print.Pdl.PostScri
Different namespaces are just that... Different, name, spaces so you shouldn't worry at all (generally) about duplicate names across namespace boundaries.
However, you should be conscious of usage. e.g. you are creating a layered app with many different layers (in different namespaces), you would not want to duplicate class names that might be shared across layers.
If you feel it is sensible to use duplicate naming between namespaces, you can always use the handy using statements for renaming in consuming classes e.g.
you have two User classes :
Data.Entities.User;
App.Core.User;
And want to use them in the same place...
You can use a simple using statement such as
using HttpUser = App.Core.User;
To alias one of them and so avoiding full qualification, and avoiding any confusion.