This is such a complicated topic that I have a hard time putting this into words.
I've attached a picture showing (as I recall making it) a 30/70 knife.
If you put the same bevel on both sides of the knife, you move the centerline of the knife and this can affect cutting performance.
The image below is very blown up and should be pretty darn correct for a 15 degree angle.
If you correctly sharpen these type knives, the bevels will not be the same size on both sides of the edge if you sharpen both sides as the same angle
Again, very blown up....we're dealing with thousandths of an inch here.
You can sharpen these different ways. You can sharpen the back side at a shallower angle and end up with bevels the same size on both sides of the knife. Or you can sharpen the back side at the same angle, but remove less material on that side and your bevels will not be even.
The key is to keep the factory centerline of the knife. If you don't, it can (not necessarily will) affect cutting performance. The more asymetrically ground the knife is and the more off of centerline you make the edge the more it will affect performance. Also, you won't notice it a lot of times based on what you're cutting. With a honesuki I think you'll see it less than with other knives. I find I can feel it most when I use a very asymetrically ground gyuto that I've messed up the center line on when I'm cutting hard, large veggies. So, not very often.
I hope that helps somewhat. And I hope I didn't screw up that explanation.