Placing empty maps around a numbered map ("Map #X") creates a large number of duplicate maps. This was discovered while trying to remember how to enlarge a map (I forgot that I had to use PAPER.)
Comments 3
Please make sure to check out the Minecraft Wiki first, it says it right there: http://www.minecraftwiki.net/wiki/Map#Cloning
Yes 1 discovered map + 1 empty map = 2 discovered maps (cloning).
1 discovered map + 2 empty maps = 3 discovered maps.