Board Thread:Game Help/@comment-27270271-20151203234423/@comment-27999576-20160402151752

You can tell if the Corruption is fake or not by seeing if there are Demon Altars in it. However, if there are Crimson Alters in the Crimson, but not in the Corruption, the Corruption is fake. IF there are Demon AND Crimson Alters, see if the Corruption has "pits" which have Demon Alters. If they're a) not in pits or b) there ARE no pits, the Corruption is fake. Glad I could help! :)