Can a company have more than one account owner?
No. Each company in Plain has exactly one Account Owner, the team member responsible for that account. The Account Owner is a single user field on the company record. It is not a list and cannot hold more than one user.
The Account Owner appears on the company profile. You can use it in workflows to route or assign threads. For example, a workflow can automatically assign a new thread from a company to that company's Account Owner.