that would dilute each by half. The correction would be cut the applied area by half to make up for it.
The water is irrelevant so do not get mentally drowned by the gallons. It has a use as a dispersant medium and even a solvent, but it is more important to mark off an area and register (sight in your sprayer) such that you know how much liquid per square area your sprayer is throwing out. To many different pressures and orifices to bother telling anyone how their rig works. Then add to those variables a few more like the fast walkers, the slow walkers, machine pumps and so forth. Sorry, you gotta do you on this important detail.
Many times the area has to be backed out of the manufacturers label, which is the law and the ONLY formula you should be following, because I may have your product too but oops! they changed something recently!. The guys on the vid were talking pounds per acre on some products. Imperial units are a pain in the potato. Metric is so much easier because 1 mL water is also 1 gram of water. If i want to make a "gallon" of 1% solution in metric then I can easily say 4000mL water is 4 liters and also 4 Kg. Since 1% of 4000ml is 40ml I can pour 40g of water onto a scale from the metric "gallon" of 4 liters, then simply replace it with 40g of herbicide regardless if the herbicide mix has more or less volume than water due to the solids or other components of which it is made up..
If someone has calculated mixtures for their product but not your blend, you have to learn what the product mass to water mass ratio is so grams are helpful since they are a unit of mass. In imperial units this is called specific gravity. In metric it is the same idea really, its just that imperial units do not have some easy relationship to water that says 1 pound of water equals 1 quart or cup or something like that so metric is far easier.
The idea of how much mass of product per 1000 square feet is going down (or square meters) is the problem to be solved.
I hope this helps clarify your questions to yourself as well. The mixture mass is no less important than the quantity of mass questions related to the volume of spray medium water.
You may find it useful when adding a third component such as a spreader sticker or a soap or non-ionic surfactant.
One reason I hate the Oz measurement is fluid ounces vs pound ounces. I am like "Enough already"! Anyway buy a digital scale. Mine (OXO brand) was 11 bucks. You can check it for accuracy because now you know 250ml of water weighs 250g. Just remember most of the kitchen style measuring cups use the bottom of the meniscus, not the top, when measuring water. Some scales will pick that mass up. I use one that measures to 0.01g sometimes.
your math in this area is better than most. What say ye?