Removal:
The most basic response to a conflict should be removal. Law firms run conflict checks before agreeing to take a case. However, in real estate firms that represent multiple competing landlords and tenants, and manage and own properties, this would rarely if ever occur.
Disclosure: The most likely scenario is disclosure. In Massachusetts Residential law brokers are required to have the buyer and seller sign a form which states who the broker is working for: if the same brokerage represents both a buyer and a seller a Dual Agency results which requires that neither agent can act as a fiduciary - that is, the agents must deal with the principals impartially and cannot divulge motivation, terms, or value leaving the principals with no counsel on these critical issues. There is no such Standard of Care for commercial real estate as all principles are considered educated participants.
The reality of Dual Agency is that it rarely starts as such, and principals may divulge information in confidence that may not have been shared had they known of the potential conflict, creating a compromised position which undermines their negotiating position.
Recusal: Recusal, or disqualification, might occur at sensitive points to a negotiation if the broker represents both sides.
Third party evaluations: Would be used retrospectively, when there is a need to determine a fair market value, or when a commission is in dispute, not to insure proper advisement during negotiations.
Codes of ethics: Guidelines which should outline how to avoid conflicts in the first place, not how to resolve ones that occur naturally in the course of day to day business, and which are embraced by firms representing landlords and tenants.