I'm wondering, if both projects were written simultaneously, and are completed and polished, if it's bad etiquette to query two manuscripts at once? One agent may have some interest in one project I've already queried, and I've been itching to begin querying a second project to a different group of agents.
I can certainly understand why you'd want to do this. With the glacial pace of publishing it seems stupid to just wait around on one manuscript when you could be querying two! Or Three! Or SIX!
Here's why you shouldn't.
You only get to sign with one agent at a time. Let's say you're querying two or ten manuscripts, and they're all publishable and they all get offers.
How do you compare offers? My enthusiasm for "Everything I Know About Sex I Learned from Tawna Fenske's Blog" may be much higher than my enthusiasm for "Everything I Know About Vodka I Learned From Barbara Poelle's Trash Basket"
But if you sign with me for Sex, you're also going to expect me to rep Vodka. So you tell me about Vodka, and I ask for the proposal, meanwhile you've got Agent Impatient waiting for an answer for her offer on Vodka.
This is NOT the time for something that would look like the second act of Noises Off! (and I mean the play not the dreadful movie version.)
The other reason that is if you query me on three "finished, polished" projects in a given year, I stop taking you seriously. I know darn good and well how long it takes to write a good novel. I have 45 people writing now and I know their every anguished scream and cry.