simultaneously diplaying two maps with different colors for each and overlap

Ok, I confess to being a novice. But I have read through the manual and spent several hours pushing buttons.

I take an asc file from Maxent, and recode it to be 0/1 at some threshold, with presence red. I do the same for another file with present blue (so, present and LGM distributions).
I can drop one map on top of the other, and see both colors, but I want to be able to see the overlap as a different shade. How do I get the area of overlap to be a different shade?

thanks, Bob Zink, U MN, St Paul, zinkx003@umn.edu