Think of it like this...
You buy a car, and after a few weeks, you notice the engine just doesn't run well -- sometimes when you press on the accelerator it stalls out, other times when you hit the brakes it revs too high, and other times it just shuts off for no good reason. You take your car to mechanic and they completely replace the engine with a different one (yes, I know this isn't exactly a common thing to do, but bear with me). So, a month later, you see that your car manufacturer has released a recall for certain parts in your old engine, which you still have sitting in your garage...so you could go back to your mechanic, have him replace your old engine and fix the recalled parts, OR keep the new engine you already installed that doesn't have any of the problems the recall is designed to fix. Either way, you can't run both and anything you fix the old engine won't change anything if you put the new one back in.