Selling second rights?

All the magazines seem to want 'first rights'. What about second rights? Can you sell a story twice, or is it sold once and that's it?

 

If anyone knows somewhere, please let me know. I have a lot of short stories and getting paid twice for them is something I would very much enjoy.

I used to use duotrope but now they have gone paid, and I don't have enough stories to cover it.

 

Publishing ... and Other Forms of Insanity: 185 Literary Magazines Accepting Reprints
This list is from a couple of years ago, and not all submissions are paid, but you can see if any of these suit your needs! Another option that you can look into is finding magazines that want exclusive rights. This stops you from offering any rights to other publishers for a predetermined amount of time. However, once that time passes, then you can sell it to other publications.

 

Do they take stories that have been online?

 

I guess the only value for a lot of them is in being the first place to have it.

Only place I've seen things like this would be in anthology collections.