Final answer:
The term describing both parties in a real estate transaction being represented by the same broker is 'dual agency'. It's a scenario that may lead to imperfect information and requires disclosure to both buyer and seller.
Step-by-step explanation:
The term for when both parties to a real estate transaction are unknowingly represented by the same broker is referred to as dual agency. In many jurisdictions, this practice is legal but must be disclosed to both parties. The concern with dual agency is that it can create a conflict of interest for the broker, given their duty to represent the best interests of both the buyer and the seller. Moreover, dual agency can be seen as an example of imperfect information in a transaction, where each party may not be fully informed about the broker's relationships or the full details of the arrangement, potentially undermining the transparency of the real estate process.