Two different colored bulbs for lamp with turtle tank?

A lady donated to me her old tank that she used to keep her turtles in along with some lightbulbs to put in the lamp. She gave me two purple-ish bulbs and one clear one. I'm not sure if one bulb is a UVA and the other a UVB or if they're the same bulb. Should I put in one of each or just put in the two purple bulbs to be safe?