To back up with what Howie said about the bulb, a 75w infrared bulb is an alright heat source but replacing the blown bulb with an identical one (100w) will be just as good. You need to take into consider that BDs are desert dwelling animals therefor during the day they need a lot of heat and at night the temperatures they would be exposed to in the wild will drop pretty low. The heat mat shouldn't be needed all of the time but it is always handy to have one as standby and for a cooler night temp as Howie mentioned.
the golden rule with reptiles that the majority of hobbiests will repeat is never keep two sexually mature males together as you will never be free from fighting for a higher position in the hierarchy as well as for territory, food and even a mate in the breeding seasons.
If this is your first reptile I would suggest only getting ONE BD to begin with as it is much easier to manage for a first timer and you can focus more attention on it to ensure you tame it to be good with handling and feeding etc. - you can always add another to the accommodation (if its big enough) at a later point if you wanted to.
2.5.0 Eublepharis macularius
1.0.0 Pogona vitticeps
1.0.0 Mesocricetus auratus