It is narrated from Sayyiduna Samurah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When two guardians conclude a marriage, she belongs to the first of them, and when two authorized agents sell (an item), it belongs to the first of them."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6813