I know the stuff. Doubling up on that dosage would not hurt a thing. I do that as a matter of course.
There are two types of diesel additives available at Canadian Tire. They also have a 3 in 1 diesel conditioner. I used this when I ran out of Kleen-Flo. it's better than nothing. It works. I also use it a little stronger than the directions on the bottle. If you know that you are going to top up the tank from half full, pour 50ml into your handy-dandy little plastic measuring cup, and pour it into your tank. Then fuel up, thus mixing it all up. Soon your diesel will be hardly smoking at all, strarting easier, and running strong. Additives are needed to raise cetane levels and compensate for the reduction in sulphur. Additives are good for the I.P., and will help to minimize the soot gunk that accumulates in the manifold.
The truth is, I really do not know if the Valvoline and Canadian Tire product are as good as Kleen-Flo, Hawes, or RedLine, but they certainly aren't cheaper - just easier to get. I like tried tested and true products that are known to work. I haven't seen many Big Rigs parked in the Canadian Tire lot, while the owner/operartor is in the store buying his fix of "Motomaster 3 in 1".