Why are you introducing them? If for mating, make sure they show signs of readiness (pacing cage, etc) before the introduction. Then put one in the other's enclosure. If there is an attack, grab both quickly and separate them. If big animals, you may want to have help standing by. No problem with a couple of Antaresia, but even then it is nice to have extra hands. If BHPs or big coastals latched onto each other, you might need more than 2 people!