You misunderstood the idea. These aren't two leads with the same power. The decisional power is split between them and each has and bring their own responsibilities and specialities.
Then who controls the money? Who approves projects? I’ve seen this coleader idea in practice in the corporate world. It lasts one budgeting cycle.
One person is in charge, one person thinks they are charge too.
Sarcasm aside, when there is a disagreement between coleaders, whose point of view prevails? When you know that then you know who is really in charge.