I bet many of us have that "extra" kickstand laying around because it was cut too short!
For a hybrid or touring bike, I like having a kickstand. On a lightweight road bike, you have to be careful if you choose to use a kickstand. Even using a Greenfield Stabilizer, there is a chance of damaging the thin walled tubing used to make the chainstays by overtightening the kickstand. Also, due to the light weight of some road bikes, it can be easier to blow the bike over when on a kickstand. I no longer use a kickstand on my road bike because the winds in my area could blow over the bike no matter how I oriented the bike in relation to wind direction.
On my hybrid commuter bike, I gladly use the kickstand, as it doesn't have the blow over problems of the ultra-light road bike and it has a kickstand bridge between the chainstays so I don't have to worry about damaging the aluminum chainstays.
Unless you plan to go on a fully loaded tour, I would think the double kickstand is overkill. I would go with a standard kickstand cut to the proper length or with a Greenfield Stabilizer before I would do a double kickstand.