I am pretty sure you should only have one cable per clamp unless design specification says otherwise.
As a general rule, it's one cable per cable clamp. There are cable clamps that are rated for more than one cable per clamp. To find out if the clamps that you have will accomodate more than one cable you would need to know who the manufacturer of the clamp is and check with them.
The pros might also know an exception using nonflexible raceway sleeves or nipples.