What @WillAdams said about rubbing is very important to keep in mind. The way to deal with it is to do the cut with a slight taper. Maybe 0.1mm or 0.2mm over the 19mm depth. For slotting, you want this on both walls, so you double the path length. For pocketing and profiling, there is no additional time involved.
Then again, slotting is hard on the tools and machine to begin with, and a good finish will often require a clean up pass. You can do the fine cut on the finish side to handle this and not get a penalty, if you want clean surface finish. This small of a taper doesn’t require fine depth grades, as the steps on the finish surface are insignificant (a few 0.01mm) if you do, say, 5mm depth of cut.