Dear Two Birds in the Hand…
Unless those editors required “exclusives,” submit to them and to agents simultaneously. Should one of the editors offer a contract before you sign with an agent, update the agents. They’ll likely review your submission quickly. (Of course, let the editor know you’re awaiting word from agents; he won’t yank the offer because of a few days’ wait.) Your new agent can step in to negotiate this contract, making her the agent of record and earning her the usual percentage of that book’s royalties. Sure, she didn’t work the submission phase, but she’ll get the most favorable contract terms for you at Book One. That’s worth her cut, and she’ll be able to field any rights opportunities (or publication problems) that arise in the life of the book. Plus, you’ll be working together fully from the beginning. If the two editors decline, any agent you get down the line will want their names so she won’t bark up those same trees. There are valid concerns about using up opportunities by self-submitting to editors, but you’re only talking about two editors. I’d go for it.