This post does not has a suggestion, rather asking your suggestion.
In the past project I worked on, I had some issues regarding exertise conflict. We worked with a external subcontractor, which brought the similar expertise to the project team. We worked on similar tasks and provided the similar deliverables to the end-customer in common.
In this situation, in a way we were placed in the competitive environment. Either of us are incentivised to deliver better results to the end customer and obtain the credit about the deliverables. We discussed, brought the ideas, and implemented them.
Anyone also has similar situation? How does it work? I feel like this is not the right situation.
If I were the end customer and need to use the multiple vendoers, I would coordinate the vendors by expertise. Each team brings one or more expertise. But it is not mixed. In this situation, each of the vendors can fully exert their expertise without any hesitation or fear of being abused.
If there is a mixture of experts across different companies, some of them started not to show 100% of their potential since they know their results might be taken by the other or they need to take a protective motion, which is a waste of time and thoughts. Maybe this is called "politics" in general.
I do not know what is called. I assume there are some books about this. It is not a special thing, I believe.