We have a website where the public and widget dealers advertise their widgets for sale.
When a widget is loaded to our system it creates a widget details page specifically for that widget and that page is indexed by google.
When the widget is sold, the page will disappear, but the page still remains in googles index.
What my web developer did (it isn't live yet) was to create a 301 redirect so when a user clicks a google listing of a dropped widget details page - the page redirects to the general widgets page, so the user doesn't get an error or a blank page.
I'm worried that this will create duplicate content, as it is the wrong way to use a 301 redirect - is that assumption right? If so which is the correct course of action so that we don't mess up our Google indexing/listings etc