You can have multiple devices all have the same email for FaceTime think of it like have two phones in ur house though they will both ring when you get a call... And you can't call yourself from the phone you are trying to receive that same call on... Simple solution is to set up a second email address... Not sure about the iPad 2 but I know FaceTime for Mac allows multiple FaceTime accounts to be added...
Facetime gives you the option to select the email address you want to use.
It would be easier to setup a unique email address for each device so you can identify which device you want to call.
Remember email addresses are free.
FaceTime for Mac allows you to add alternate email addresses, does FaceTime for iPod/iPad not allow this also?
What I am really waiting for is to be able to link emails and a phone number. I'd like for my Mac to ring when someone tries to FaceTime my phone number (and for my iPhone to ring when someone tries to FaceTime my email address).
If you have multiple FaceTime devices: iPhone, iPad, iPod Touch, Mac, Multiple Macs, etc. The iPhone's ID is the phone number, but the rest use an e-mail address. If you don't want them all to ring when someone is trying to contact you, then they each need a different address. You could set up a separate e-mail address for each device, but that's a pain.
All you need to do to have multiple IDs per e-mail address is append '+something' to the e-mail address. For example if your e-mail address is email@example.com and you wanted to have a separate FaceTime address for your iPad and for your Mac you could use: firstname.lastname@example.org and email@example.com.