Dearest, most beauteous Miss Snark, who is all-deserving of endless pails of gin, clue guns equipped with dilithium hyperdrives, and an immortal George Clooney love slave:
Is it considered 'common courtesy' for an editor to inform other publishers with whom Author X has published that she is considering a ms by Author X?
The long version: Author X published a novel with Publisher #1, with an options clause in the contract for 'future works' . Publisher #1 was aware of the existence of numerous previous novels by Author X, which were on submission to various other publishers. Publisher #1 required the options clause to include all genres despite only publishing one genre. Publisher #1 subsequently rejected four novels by Author X that were not within the genre, and accepted one within the genre. Author X queried Publisher #2 with one of the rejected novels, which had been written well before the contract with Publisher #1 had been signed. Publisher #2 replied with question about the status of the ms and whether it was free of an options clause.
Author replied in the affirmative. Publisher #2 then requested the full ms but noted they had already informed Publisher #1 of this request, as was common courtesy practice between colleagues.
Author X considered this a breach of privacy, not common courtesy, as Author X thinks it's none of Publisher #1's damned business what Author X does with her rejected mss.
What does the glorious Miss Snark say? (Besides "get an agent". Author X would kill for an agent, truly, but unfortunately writes for a niche market -- gay/lesbian -- and small presses don't offer advances or anything else that would interest an agent.) many thanks, bonbons, confetti, and earnest wishes that George Clooney arrives on your doorstep soon,
I'm not sure what planet you live on if you think people in publishing don't talk to each other ALL the time about things just like this. In fact, talking about stuff is so much the norm, that not being able to talk about something is red hot news.
Given you don't have an agent, a publisher would be stupid not to make sure you're representing your situation accurately when you say you're free to publish with them. They're just avoiding problems. If you don't like it, don't take the deal.
"Expectation of privacy" is a phrase used about information on your tax returns, banking and libraries. You don't enjoy any expectation of privacy about making a business deal. We're not giving people your credit card info, we're talking about your book. We're going to talk about it to a LOT of people before you get an offer let alone accept.