First : If it's legal copy from your own PSX games, thats no problem. We only have problem with downloaded ISO / illegal copy.
Second : it depends on how you make the copy. Using Nero wouldn't be good. In this case, CloneCD and Alcohol 120% do their job very good. I suggest Alcohol 120%, since it's also have option for DVD recording [may be unused for you

] and compatible with CloneCD. It also have built in virtual CD / DVD ROM.