They really aren't that far apart in weight, and its probably something like 1 ml/500g (dont know exact dose recommendation, just a guess off of what you were told) or something so, for example, I don't know why you would do 2.1 for one and 2.3 for another when that is kind of hard to measure. Remember, this is the safe level for dose, not the toxic level. So they will be fine.