The are designed to be dosed in equal parts and only allow for a very small leeway in dosing unevenly without disrupting the ionic balance and trace element replenishment in your tank.
This was Bob Stark's (the founder of ESV and creator of B-ionic) response to the same question on another forum:
"Due to the proprietary nature of some of the formulation, I can't divulge where certain ions are located with regards to the liquid components, but can tell you the Comp A supplies all the calcium and the portion of magnesium not supplied by the dry magnesium sulfate, and the Comp B liquid provides the alkalinity plus some other ions. If one alters the amount of these liquid components then yes, these other ions will also deviate. My guess is a 10% lowering of either component will still result in an acceptable mix because these other ions will only drop by 10%. I can not make any guarantee's the mix will be suitable for all uses if altered however and leave that decision to the individual aquarist. If you're testing for calcium, magnesium, alkalinity, potassium, and using individual additives to tweak any of those deficiencies, you'll probably be fine if you don't reduce the liquid components by more than 10%. I hope this info helps and thanks again for using our products!"
If you ever have a question about an ESV product, don't hesitate to email them directly. I have a few times and Bob usually responds within a day or two.