I met one of my favorite editor for drinks the other day and we were doing our usual kvetching about being overwhelmed with reading.
The editor then tells me this story:
An author queries me directly - it's not my stuff but it sounds interesting so I pass it on to a new bright eyed and bushy tailed assistant editor who's looking to build a list. He likes it and requests it. It arrives and goes in the pile of not-terribly-urgent.
Time passes, as it does.
Author who sent full signs with an agent.
Agent then sends out a new and different project. Neither the author nor the agent let our bright eyed and bushy tailed assistant editor know about this - nor is he the editor to whom the new work is submitted.
The editor who gets the second submission reads and likes it, then gets it read by the powers that be, gets an offer approved, and makes the offer. Only THEN does the agent tells editor #2 that "oh, gosh, Editor Bushy Tailed" happens to be looking at something else by the same author.
And of course it turns out that Editor Bushy Tailed has read the first submission, likes it, and has it with two other colleagues to get supporting reads before going to editorial board.
Editor Bushy Tailed has now wasted his time and the other editor's time because there can be only one editor for an author; the editor-in-chief is now involved much to her chagrin and dismay; and Editor Bushy Tailed has to turn over the book he's been looking at to editor #2.
Long story short - both author and agent knew two editors were looking at different projects in-house and didn't tell either editor.
Here's what we can learn from this: when you sign with an agent, tell all the editors looking at your work that you have an agent now AND tell agent what editors are looking (and have looked) at your work.
You do this even if you think every single submission has long since been forgotten. You do this even if you think it's useless. You do this so if someone doesn't know it's not because you didn't tell them.
You might be tempted to say "Bright Eyed and Bushy Tailed Editor should have let author know he liked the book." Maybe so. But face it, "should" doesn't get us very far here. This is your career. Make sure you keep your ducks in a row.