Should I start with 1 hive or 2 hives?
The highest cost of beekeeping is the initial investment. If starting 2 hives is cost prohibitive, starting with one is fine. A second hive will mean more labor/time in working bees. Although, it will probably take longer to light the smoker then it does to make a quick queen and strength check. The advantage of starting with 2 hives is if something does go wrong with 1 hive (i.e. queenless or hungry) you have a second hive to share food and/or brood. For beginning beekeepers having a second colony can help them know if something is wrong with the first colony. If a new beekeeper has a queenless colony they may not be aware if it is the only colony they have. However, if they have a queen-right colony beside the queenless colony they will easily notice a difference between the two.
There is no right or wrong answer to this question. It is up to you to decide what will work best with your apiary.