Yes, you can use Renilla luciferase reporter vector together with your firefly luciferase reporter. The Renilla luciferase works on a different substrate. However, when you co-transfect an expression vector for a transcription factor you have to make sure it doesn't affect the Renilla reporter, or else you will be altering your "normalization". If the transcription factor activates both your firefly luciferase reporter AND your Renilla luciferase reporter, then the net effect could seem like no activation, when in fact there is activation. People don't pay attention to this detail when they use a kit with Renilla vector as a "control" and they get stupid results.

I was surprised to see that my supervisor answered my question. Thanks a lot Dr. Stewart.