I'd think sharing the plan of building two versions of the same thing and tasking the teams to come up with two distinct implementation strategies would provide

I'd think sharing the plan of building two versions of the same thing and tasking the teams to come up with two distinct implementation strategies would provide a better outcome. This way there's still competition, but of a friendly kind. The risk is further diminished by communication of lessons learned and not having to step on the same rake multiple times.