1: A bot is a programme that acts as a player in game. It can be run all day and never need to take a bathroom break or eat anything! You can set your bot to do any number of things. From Baal runs to magic finding to leveling.
Some bots are still usable on BN. However, everyone who uses a bot, runs the risk of their account (the one the bot is using) being banned should Blizzard decide that they should.
2: A dupe is an item that have been dupliated (duped). In other words, one item that has been used to create many of the same item. The original item remains legitimate and the doubles are called dupes. Dupes may "poof" when in the same game as another of these dupes with the same item code (made from the same legitimate item). However, runes that are duped become permed (permanant) when used in rune words.
3: Sadly there is no real way to tell if the item is a dupe. We simply have to go on peoples word. However, if the user has a bot log (bots keep a log of what they find) to prove it is real, then you know for sure it is legit. Another way of knowing is, if the price is really low for the item you are buying, there is a good chance it is a dupe. Mostly, it's a gamble.
I hope this has been some help!
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