Well I guess I would ask what you consider a severe drop in temps at night. If it doesn't get below 60 degrees I don't think you would need any night heat. Also, if you do need the night time heat maybe get an additional light to heat your beardies basking spot during the day.
Another thought, if you use the same bulb to heat at night as during the day your night time heat is probably way too hot. A night time drop in temps is beneficial to a healthy dragon.
If you decide you want to get a different day time light what kind you get depends on where it would be situated. If it is going to be suspended on top of a screen top and the highest point in your enclosure you dragon can bask at is low then a halogen spot would probably be good. If your basking spot is near the top, which I'm guessing it's not due to the placement of your flourescent, you could use an incandescent or a halogen flood. If you decide to go with anything make sure you remember you don't need to spend an unreasonable amount of money on a bulb made for a reptile. Any halogen or incandescent from a regular store will do just fine. That's not the same for the UVB bulbs though, they are made special.
You may also want to invest in a dimmer to be able to adjust the amount of heat/light your basking bulb may be producing. That way you don't need to have 3 different wattage bulbs to try. Or if you have the ability to raise or lower that bulb or basking spot that would be adequate as well.
Hope this helps!!
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Rob Talkington