Meh. Ilford's
datasheet is excellent.
It lists both numbers everywhere: for diluting from a concentrate and from a stock solution. It just offers you an optional trick for easy and precise measurement. Kodak HC-110
datasheet offers to do the same thing! Otherwise both of them use a very clear language to describe dilutions from the concentrate and developing times. I can't see how anyone can be confused by it. But HC-110 is gone now, so just buy Ilfotec HC, RTFM and be happy.
Just like with any well-designed product.