In gaming (especially MMORPGs popular in China like World of Warcraft), 副本 means 'instance' or 'dungeon' - a separate copy of a game area. 打副本 means to run/clear a dungeon.
mistakes
Don't confuse 副本 (copy/duplicate) with 复制 (to copy/replicate as an action). 副本 is the resulting copy; 复制 is the act of copying.