Okay, I might have messed up. I have two copies of two different books, both of which are WL. I posted each one, and both were requested. I tried to post a second one and it seemed like the system took it, so I posted the fourth book. Then I went back to see if the two new ones were requested or on WL hold and I can't find the other two (one of each book). Now, in the past when I tried to post multiple copies, the system wouldn't let me. I thought this time, since it seemed to take them (I thought since the first two were spoken for) and I didn't get a "you-can't-do-that" message like I had in the past, it was okay. Then I thought, "hmmmm. Maybe it didn't take them and I missed the you-can't-do-that message". So, me being the curious one, tried to post the fourth book again. It said it was posted, but it's nowhere to be found on my shelf. WTH am I doing? I'm just trying to make one trip to the post office today with 4 WL books. 

You aren't supposed to be able to post a duplicate book until the 1st one is marked mailed.  This is to give equal chance to everyone who might have the book. 

Also posting all them today is no guarantee that you can mail them all today. 

I love your lemon. Or is my color off and it's a Florida orange?

As Mary says, it's a precaution built into the system.  Another reasoning, is so members cannot accidentally post a book more than once if they only have one copy. 

And the avi looks like cheery (and sparkly) orange on my monitor.

I think it's an orange. 

I vote for orange too.

I also want to second that just because it's WLed that doesn't mean the people will accept right away, they have 48 hours to respond, unless there's a little "a" by the larger "w" indicating that it's on autoaccept. Then sometimes they don't take it giving the next person another 48 hours, so you can't assume they would go through today anyway. 

Ah, well... you can't blame a gal for trying ;)

And I vote orange too... although I suppose it could be a pink grapefruit. But Mary, for you, I'll call it a lemon   

Heck, request a book from me and I call it a banana if you want!