I opened a support ticket with dreamhost but I figured I'd post this here as well just in case someone can corraborate my experience.
I noticed the past few days that I've been getting duplicate emails. The duplicate will arrive a few hours after the original, yet have the same exact timestamp as the original. I would normally poke around on my machine to see what's up, but interestingly my wife noticed the same exact problem in her own email on her own machine. I then emailed some clients of mine who I turned onto dreamhost and one of them replied (so far, it's the weekend of course) that she was experiencing the same thing these past few days. (funny, she's one of those type of email people that will immediately go through her inbox and either delete or file away emails... she thought she was having a case of dejavu seeing the same email hours apart
Anyway, further info is that we're all OS X users, I'm using Apple's Mail program, my wife is using Eudora, and my client friend is using MS Entourage. So that further makes me think it is in no way related to our client software but something to do with a pop-server.
If anyone has been experiencing the same thing, by all means let us know. Maybe we can help pinpoint what's going on.