Although I agree that it could be problematic, and might not be 'Best Practices' for many types of code, the general concept could have its uses.

I would prefer instead of handling this by moving things into the main namespace, that you instead force a qualification:

Which would then allow you to call the packages in "My::Company::Namespace" with the alternate prefix "MCN::"

You could then import/alias multiple namespaces, and just give them different aliases.