I have a quick question. I know that lungo is less concentrated than a regular shot of espresso, so if I pour a lungo into two cups at the same time, as I guess most machines would let me do, will I get the equivalent of pouring two seperate espresso shots or will I just get a weaker tasting espresso in each cup? Should I instead use a double lungo for this?
A lungo is an espresso that is pulled for longer and thus more water flows through the grounds. Plainly speaking it's just a bad way to dilute espresso, because you are extracting more of the bitter compounds that you don't actually want to have in the coffee.
If you want to fill two cups at the same time, you'll have to use a double basket (with two spouts), which means that you will also pull a double shot automatically. Using the double basket means that you also need double the amount of coffee as compared to a single basket (with one spout).
So pulling with a double basket will give you two separate lungo shots, one in each cup. If you put a large cup under both spouts you will get a double lungo.
The better way to dilute espresso is to fill the cup with water (to your taste and strength preference) and pull a regular shot in the cup with water already in it in order to make an americano.
Your espresso will be the equivalent of making two separate shots in taste. It won't taste any different or be any weaker because you are splitting one shot into two cups. The only difference is that you will half as much volume in in each cup compared to letting the shot pour into one cup.
Alternately some people would let the double shot run into one cup.
To get a standard volume in each cup you should use a double basket or choose a double shot. So yes, a double luongo split into two cups is what most people would do.