A party acting as a representative once, may not be a representative twice.
In the absence of a validly conferred power of attorney, the principal shall only be bound if the third party can rely on its own legitimate representation of the situation.
Contract for the chairman of a listed company: how to manage a conflict of interests?
A stock corporation whose board of directors is reduced to two members due to a dispute among shareholders cannot validly enter into a contract of mandate (director) and employment (manager) with the chairman of the board without violating the prohibition of self-contracting.