Where does “ⲉⲧⲃⲉⲟⲩ” come from?

ⲉⲧⲃⲉⲟⲩ (Coptic) comes from Coptic ⲟⲩ, from Egyptian wꜥ — alone; unique; as one, all together.

ⲉⲧⲃⲉⲟⲩ (Coptic): why?