Digital BW, The Print

I printed a yellow patch and then ran the paper through a second time
and overprinted with a cyan patch.  The reverse was also done, first
cyan then yellow.  A third paper had one patch with 100% yellow and
100% cyan printed in one pass.  All three looked different.  

It seems to get the correct blend of two colors, or grays for that
matter, each dot must be printed adjacent to another but not on top of
one another.