Im not sure but to find out make a skeleton kill a creeper with an bow.Just hit a creeper thats near a skeleton.Be careful though.You should get a music disk when the skeleton kills the creeper.Then you can see if its an diffrent disk.If so,Then your lucky.That means there are more.
Go download Redlever Now!
Once we get the 1.2.3 update, there will be 11 in all I think.