My sons have and use iTunes on our one laptop. I have an iPod Shuffle and would like to open a separate account at iTunes using the same e-mail though. Can I do that?
The answer is, quite clearly, no. If this were possible, how would Apple distinguish between the multiple accounts?(That's a rhetorical question. I'm sure there are many ways to go about his, but it would be extremely annoying and inconvenient for both you and Apple).
However, if you are not to keen to set up a new email, you can still set up a new Apple ID without an existing email address. And if there are any songs, apps, movies, etc. you want to be on both accounts, use Family Sharing.