I too raise tomatillos, I plant two of everything much for the same reasons as beefstake mentioned. That said I would really like to know from plant specialist if it is true you need two. I have read all kinds of conflicting data. Some say no, some say yes.
This year my tomatillo plants, two of them varied in getting started. One took off like a race horse and the other more like a mule. The race horse produced flowers and then husks before the mule did, so I know there was no cross pollination. The mule has since learned to run and it is going strong now, so now I may be getting tomatillos.
I know this does not answer your question but hopefully someone can so we both can know.