Mukhtasar Bukhari (Abridged) 1851 — Do not propose over your brother's

Narrated Ibn Umar (may Allah be pleased with them) that the Prophet (peace and blessings of Allah be upon him) forbade that a person should bid over the bid of his brother, and that a man should not send a marriage proposal over the proposal of his brother until the first suitor leaves the proposal or gives permission to the second man.