you can safely mix benzos but just bear in mind that they are all going to add up, take a look at the equivalency chart linked at the top of the forum for half lives and dosage equivalencies for tons of benzos.
I used to mix xanax and clonaz regularly, I never really felt like they cancelled each other out, mixing any benzos will kind of just make you feel more benzod in general, you can normally pinpoint parts of each benzo in the effects, also remember that different benzos are built for different things, hypnotics, anxiolytics, etc, so even though you might not feel as sedated from mixing two different benzos, one may be more prone to sedation than the other, the effects will still combine though, so don't overdo it.
As a side point, if it is only other benzos that you are planning on combining with xanax then risk of death from OD is pretty low, it's almost impossible to die from a benzo overdose unless you mix with alcohol or other downers, most common risk of death would be doing something ridiculously stupid because you have taken too much and are acting without inhibitions. As I said before, don't overdo it, you could end up very fucked without even realising it, has happened to me in the past on a few occasions.