Only if you have multiple rigs I believe. But even if you could mine all at once on a single rig, you would divide your revenue among the coins. So if you had $1 in mining, you would then have $0.25 in each when mining 4 coins, so there really is no point in doing so. Just mine whatever brings the most $ and then trade the profits into other coins if you want to hedge or invest instead of cashing out.