In June I wrote a piece of software that will take all of the loudspeakers in a MAPP XML file and mirror them across a line. The most common use for this is in venues with a significant surround system that is symmetrical about the center line of the venue, though it has also come in handy for stadia with two axes of symmetry. To use, just open the MAPP Mirror application, select the original XML, and go through the options.