I use a recurve and longbow. Getting good at this took practice, like a lot of practice.
First. There are some very expert opinions out there on why this is fake and or a bad idea but there are some problems with that. Most people aren't thinking of the bow as a weapon of war. They are thinking of it as a hunting/sport weapon. They are thinking of compound and recurve bows where it is pretty much a given that you are going to be using bow hand draw and not arrow hand draw.
Second, the physics around arrow flight are really REALLY complicated. So complicated that for a long time people thought bows were an impossible mechanism leading to the coining of the "archers paradox" now I'm not going to get into the specifics but suffice it to say that the loss of acceleration is correct but not as dramatic nor as important as you'd think in the context of a battle.
third thing is, Arrow hand draw is important which means owning a bow that allows you to do this is important, you can get a longbow, and if you are interested in them I highly reccommend it, or you can just get a recurve for the opposite of your dominant hand and sand the grip to shape it a bit. Professional olympic archers can fire an arrow maybe every once every 3-5 seconds an ancient archer could fire an arrow about once every second. The reason is arrow hand draw lets you rest, nock, and draw the arrow as a single motion rather than maneuvering the clumsy bow hand draw. This is going to help you keep the top arrow from going off course or worse, interfering with the flight of your other arrow.
fourth thing, in sports and hunting accuracy is important, in battle they are important but the MOST important thing is how many arrows you can put down range within a specific amount of time. It may not surprise you to learn that people really don't like getting shot with an arrow, so the less of a break in the screaming bodkin-pointed death missiles there was, the less of an opening you presented. Also the average range for an archer to be shooting at individual targets in battle is 170-200 feet at most otherwise they would just be firing into the mass of people hoping to hit. So you don't actually have to get it that far.
So to pull off the famed "multishot" you need to knock two arrows, I know theres a lot of ways to do that and some people use a mechanism to aid them in having a clean release. I've personally found this is the worst way to do this trick so I would avoid it. The method I've always used is one finger above the nock and two below but for this you are going to make an "arrow sandwich" with one below the first arrow one in the middle and one on top of the second. and you need to grip the bow so that your index (pointer) finger can extend and the tip can rest between the two.
If you did it right both the arrows should be perfectly straight.
Now here's the part that's going to take practice. There are two things i've found that generally make this trick work reliably. First, and most important, once you release the string your index finger needs to slide out from between the arrows, otherwise the hens (the two matching coloured flights) are going to sting it on the way past, your instinct is going to be to curl it back in but what usually happpens when you do that is it deflects the bottom arrow down. The best thing to do is to flick it straight out so it's out of the way, this may deflect the top arrow up a bit but over a longer distance it will drop back down and you should still get a pretty accurate shot. Second, draw the bow with only your middle finger, keep rour ring and index finger extended to stabilize the arrows but you should be pulling from the middle, the reason for this is, while the bow will deliver all of its force across the entire string it delivers the greatest acceleration from the point you drew it back, for maximum accuracy this should be directly between the two arrows.