Is it not allowed?

?

Nope

No. It's not.

I find when I play on a real board my game suffers considerably, since my perspective is different. I miss things I should see. Your idea is a good one.

Technically yes, but no one cares since it's an unenforceable rule.  If you're using that second board to move pieces around though and analyze, then you are actively cheating.  It's also unenforceable, but you should at least feel a little ashamed of yourself.

Well, unless you're playing by correspondence (Daily) rules, in which case you can have as many boards as you want and move pieces around to your heart's content.

In correspondence/daily chess you can even self analyze on chess.com itself as it keeps in the spirit of correspondence chess. In live chess it is considered cheating if you're moving the pieces around to analyze.   However, if you're just moving the pieces to mirror the game its fine.  

I know someone who recently started to mirror some of his games of 10min or more because he saw that he had a big drop in play between online and OTB. 

okay, thanks for the answers!  My conclusion is that it`s not allowed to move the pieces around to analyze, see what the outcome would be after a certain move, but it is allowed to mirror the game on the screen!

I have played too much online and it has affected my board vision for otb games. Since I'm a working professional without too much spare time to go find otb games, I will play 15/10 games where I make a move on my board, make my opponents move for them, etc. I don't move pieces around to test out positions mid game, and I'm trying to recreate a tournament type feel. I have never considered it to be cheating.

Illegal? No. Against the chess.com rules? Yes. They consider it "outside assistance" and therefore not permissible. It's a stupid rule obviously and they'll probably soon consider allowing the use of a real board.

Yes, i agree.

That's the reason my friend has for starting to mirror his games.