I kind of agree with @Cathryn above. I have worked liked this for years although I had worked as a SENCo Whole School. with a deputy SENCo in the Secondary phase. I took Years 7 and 10 (Transtion year groups ks2 to 3 and KS3 to 4.) and my Deputy handled 8, 9 and 11. I have never experienced two SENCos in a single school. But its nice to know such positions can be created.