On mail accounts form, pressing save and test followed by save creates a duplicate account
It's a regression in that the button itself is a recent addition and you couldn't make duplicates this way before, but it's not like something that was working is now broken, and it's easy to clean up after.
Haven't looked too close yet but I think it's because the test button doesn't submit the form, so the form never gets an "id" set, so then when you click save after it's like a new form.