Need? That’s easy -just one. How many SHOULD you have? At least two. When you first kick off your beekeeping life, it is fair to say there’s a little expense ahead. Thankfully many of these expenses, the smoker, the hive tool and so on, are one time costs as you use with any hive.
Purchasing two hives does add a more cost, but the utility you gain in doing so is often well justified. The new beekeeper won’t really have a good sense of a strong versus weak hive. Having two hives (initially of the same type) allows comparisons to be made easily which can lead to earlier detection issues. Additionally, in some scenarios a problem with a weaker colony can be addressed by moving frames from a stronger one. Having two or more hives significantly improves your understanding of bees in that first year.