Updated to suggestions made by mbaxter
Updated the PR as I now have a better understanding of how the wither head system works, the CENTER head (id 0) takes charge, the LEFT head (id 1) and RIGHT head (id 2) aid the CENTER head in shooting at targets, they will either shoot at the same target or targets around about the CENTER head's target. Thus the CENTER head can and will overwrite the targets of the LEFT and RIGHT heads. This means in a couple of cases whereby I was setting the target of all heads, I should've only been setting the target of the CENTRE head. I think, from my testing, if the CENTER head doesn't have a target but the LEFT and/or RIGHT do, they work independently. I am still not 100% sure on the information before, if you know more, let me know.