Contrary to popular belief, It is extremely hard for a cham to overdose on calcium. Calcium is water soluble, so if there is an excess, your chameleons body will simply excrete what it doesn't need, which is why it is important to keep them hydrated. So in short, yes you should still dust AND gutload with high calcium foods.
Don't think of it as supplementing with calcium when you dust with calcium, think of it as correcting the calcium: phosphorus ratio imbalance that feeders like crickets have. Most feeders have a large amount of phosphorus in their body's, and low levels of calcium, so we dust with calcium to balance out the ratio. High phosphorus levels in the blood over time, lead to health issues.
Can't quite make out what you're trying to saying with the ''with none and once is his vitamin'' part of your post but you should be dusting with PLAIN calcium at every feeding, and dusting with calcium WITH D3 once a month, and dust with vitamins ONCE-TWICE a month also..depending on the specie.