Offer your thoughts or opinion on the input financial query or topic using your financial background.

Why can't I open multiple sell orders?
From the message you report, it sounds like you are trying to sell the same shares twice, you have two open sell orders for the same shares. Either you have accidentally entered two sell orders, or the web site is having a technical problem. I'm not a customer of Fidelity so I can't say what their web site looks like, but there should be some screen that shows your open orders. If looking there doesn't resolve the issue, call customer service.