@ flyingdumbells and strato
You can get a MPL licence with a CPL. I should know, I already had a CPL when I entered into Clark Av (re branded Alpha Av Group), as did many other fellow students. With some of the students getting 100% free scholarship while the rest of us getting a 50% discount from Alpha.
What you cannot do is jump the core flying just because you have a CPL already. And just so you know, in some ATO's in certain countries that have the MPL in their CAR's there is a conversion process for MPL to CPL and visa versa.
Its not as black and white as strato mentions. then again almost everything strato has ever said is more in the spectrum of grey and blur.