Isn't that the definition of a race condition, though? In this case, the builds are racing and your success is tied to the builds happening to happen at the right times.

Or do you mean "builds 1 and 2 kick off at the same time, but build 1 fails unless build 2 is done. If you run it twice, build 2 does "no change" and you're fine"?

Then that's legit.