I'd be amazed if they're not eating their own CodeCommit dogfood.
Amazon as an organization is pretty modular - they have teams working on lots of different projects and technologies. While I would expect the CodeCommit team to be using CodeCommit, it wouldn't surprise me if other teams used other CVS systems. You can further splice that by teams on projects under AWS, teams that work on devices, teams that work on their shopping, teams that work on physical distribution, etc.
Sounds awful. I'm a victim of their business modularity, as I need to get structured metadata into their various national systems, and their vendor-facing systems, support, and documentation are a shambles.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.