Two in a box model is an Anglo Saxon model that works well with Anglo Saxon people. They understand the grey area and they handle the positive tensions in the right way. Depending of the situation and the need of the organization each part of the box makes decisions and the things run with “back and forth” discussions.
Unique direct report is a Latin model , you report just to one person and there is an unique direction (wrong or right) to follow.
When you implement a “2 in a box model” on a mainly Latin organization, the situation is different. Generally, we try to find who in the “2 in a box” who has really more power, and then follow it. It takes time to understand how to articulate these tensions in a positive way so the organization advance properly.
I’m writing using the context of the “stereotypes”, so please consider that not every single person falls on it, it’s just a generalization.