I have seen this 3 times today. I place an order at an easily recognizable price and leave it for a while. I come back to check, and a bot has placed an order over mine with the exact same value. The bot's order gets taken, and my original order is left behind unpurchased. 

This is not right. Orders should be First In First Out.

This just occurred at about 2016-07-15T06:00:18+00:00, I had a standing order at 3.666999 for 359.215 Steem that had been there for at least 2 hours. A bot placed an order on top of mine, at $3.666999 for 4989.937 steem. The bot order was filled, and my order was left. You can see the pic it did the bot did same thing to both my Buy and Sell orders that had been there for hours...

https://i.imgsafe.org/88b7ee9f46.png

edit @dan: is what rainman said true? are the numbers displayed incorrect?