One reptitemp 500r can set two heating pads to the same temperature but not to different temperatures.
When you get it, put the thermostat probe on the UTH OUTSIDE the enclosure. Aluminum tape works best for securing it. Then with your thermometer probe right on the glass where the UTH is, adjust the knob on the thermostat until it stays around 90*F.
I am a little confused as to why you want two heating pads?