Help to understand "mirror" game setup

[RedDevil]

that's pretty much the Gist of it..

Some players however, don't like to play them simultaneously
(they prefer 1 at a time, starting the mirror after the end of the 1st battle)
And
others don't like exact setup copies (they want the same settings but a new map and kit)
Ask your OPP which he prefers

you'll find all sorts of diversity here, just takes a few games to find those most compatible to you.