It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) performed the aqiqah for Hasan (may Allah be pleased with him) with one ram and for Husayn (may Allah be pleased with him) with one ram.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11806