Dumb question have a couple of charters they have the same connections but slightly different output ie. 4.75v 0.55a vs 5v 0.5a vs 5v 1a
I have already used the wrong charger a couple of times by mistake and it seemed to work. Am I risking damaging the phones?

Depends on the phone I suppose, but you should be fine there. They’re not a million miles from each other.