Having one agent representing both parties in a contract is an ethical problem because it simply isn’t possible to fully serve the interests of either party.
Imagine if a lawyer represented both sides of a legal case – this is no different. In fact, in North America, an agent can lose their license for doing that.
The European system needs to evolve to become more ethical. Only through sole representation – in which an agent represents ONLY the buyer or the seller on price, contract conditions and more – can we provide a result that is best for our clients, and ultimately, for ourselves.