That type of hood generally doesn't have a reflector (or a very poor reflector) so you'd lose a lot of light. When looking at the bulbs just look at the actual wattage, it doesn't matter what the incandescent equivalent is. So the second bulb would just be 10 watts. Two of them would still be low light for a 10 gallon tank. I had 2 15 watt T8 fluorescent bulbs (total of 30 watts) on a 10 gallon tank and it was still low light since the bulbs didn't have decent reflectors. If you only want to grow low light plants like ferns, anubias, crypts and mosses you'd be all right. Most other plants would struggle or die due to lack of light.