By default, Cloudinary assigns randomly generated public IDs to your images. This prevents conflicts between your dev and production images. It also allows you to view the production images from your development environment (no need to sync assets between accounts).
If you use your own public IDs, you can add a 'dev_' prefix to public IDs of images uploaded in your development environment.
As well, you can open an additional free account and define different settings for each environment in your configuration (e.g., cloudinary.yml in Ruby).
Regardless, we are working on adding support for multiple 'clouds' per account and allowing for even simpler separation between development and production assets.