Why do some elements have multiple Ionic charges? Like the transition metal copper, why can it form both Cu + and Cu2 + ions?

Due to the phenomena of Orbital hybridization the S and P orbitals can Hybridise to form a new Orbital with an intermediate energy level because of which electrons can exist in different energy levels to become stable, another reason is that orbitals are most stable when half full or completely full (for transition metals its mostly d so either 5 or 10) because of which they can also show different no of valence electrons for donation to form ions.