In the hadith of Sayyiduna Uthman bin Affan (may Allah be pleased with him), the manner of the ablution of the Messenger of Allah (peace and blessings be upon him) has already passed: "Then he (peace and blessings be upon him) washed his right foot up to the ankles three times, then washed the left foot likewise."
And in this there is evidence that each foot has two ankles.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / Q357