Sure. Then if one hard drive dies, your data should be safe.
If one hard drive goes faulty and starts corrupting data, there's a reasonable chance it'll corrupt the data on the other. If the mb controller or psu go wonky, both will die. If you drop the box, both die. And so on.
Raid is for high availability servers. If you don't care about five minutes downtime, or even an hour's downtime, you want one hard drive and a second as a backup, in a draw. Possibly a third in a draw at work. Not raid.