People often ask whether they should start with one pound or two.
I sell both and I think this is a matter of personality more than anything else.
If you are patient, start with one pound. If you are not and can afford it, then start with two.
I generally recommend starting with one pound. Your up front costs are less (in the rare event that things go awry) and you get to know your worms as you build their population.
Twice as many worms simply means that you can put in twice as much food.
Both bins will eventually end up in the same place. The one pound will eventually catch up, because there is only so much space in a worm bin and you only have so much food to add.