Exactly what do you mean by too hot , what temperatures are you seeing in the bedroom and when ?
What I consider nice , a person who lives in the UK would literally be passing out in as it's warmer than they are acclimatised to.
What temperatures are you running at the basking spot, the warm zone in the existing beardie tank and how are you measuring them ?
Is the lid of the tank solid timber or flow through mesh ?
I recommend replacing the lid on the viv with a solid timber lid (with small air vents) and do the same with the second tank, you can then get the same temperatures in the basking spots and warm zones as now but will need less basking globe wattage to achieve these temperatures .
So rather than wasting the heat by allowing it rise and pool at the ceiling ,the heat will be kept in the dragon tanks where you want it.
See
viewtopic.php?f=34&t=236332&p=1816614&hilit=heat+transfer#p1816614