The Prophet ﷺ said, "None of you should propose marriage over the proposal of his brother."
أخبرنا قتيبة قال حدثنا غندر عن هشام عن محمد
عن النبي ﷺ قال لا يخطب أحدكم على خطبة أخيه
Muslim narrated it, in the Book of Marriage, Chapter on the Prohibition of Combining a Woman with Her Paternal Aunt or Maternal Aunt in Marriage, no. 1408/38, from the hadith of Hisham bin Hassan with this wording at length, and part of it comes later, no. 3297. Muhammad here is Ibn Sirin.