Ask HN: have you ever marketed the same product under two different names?

I remember that, a few years ago, two French smog check companies had ad campaigns explicitely comparing each other, even though they were actually owned by the same group and were providing the same service, just under two different brands.

The goal was to raise awareness of both brands at the same time and make each other look like a leader in the market: if company A is comparing itself to company B, it must be because company B is a leader. (didn't Fedex do something like that by presenting itself as #2?)

I can find plenty of reasons why it would be a terrible idea: brand dilution, distraction from actually building the product, extra work…

But I can also think of reasons why it might work: you're effectively A/B testing your whole branding; if you create a market, having two "players" makes it look more important; in some cases, people want to be able to compare, even if the products end up being the same thing, etc.

What do you think? Have you done it? Do you have examples of successes or failures with that?