Because they are pronounced differently. It's ah-ee-ko. Three syllables. Not 2 (ie-ko). Like
Mikhail is myi-khah-EEL, but
Mykhaylo /
Mykhailo is mi-khie-lo. My country (Ukraine, Украина/Ukraina) in Russian, is pronounced like oo-krah-EE-nah, not oo-KRIE-nah. Does this make sense?