TL;DR: If you have two bosses (officially or otherwise), you probably are in a matrixed organization, and you probably have a few problems that can be solved with this canvas.
For employees and managers in matrixed roles, life is hard.
That's because consensus is hard, and the whole dual-reporting thing was designed around consensus.
But in general, managers tend to focus on the individual, rather than the system.
What’s going on with so-and-so? Why can’t they keep up?