However, there was only one Hasselblad on the earliest missions. I don't know for sure but guess the payload margins were so tight they just didn't have the weight to spare for a second camera. You can read about the equipment carried on each mission at the Apollo Lunar Surface Journal.

They were literally sweating ounces (grams) on the early missions. I read once that NASA at one point was going to offer a million dollar prize for each pound someone could reduce from the Lunar Module. Pete Conrad was heard to quip that he was "20 million dollars" worth of reason to get the first moon landing since he was the lightest Apollo astronaut by 20 pounds. What a guy!