If you’re a business owner, most likely you want a Twitter account separate from your personal Twitter account. It can get a little chaotic to have two separate accounts under two separate emails. If you’ve tried to combine two accounts under one email, you are aware that according to Twitter it is not possible, and you get the “Email has already been taken” message.
However, there is a simple way to work around this and use the same email address with both accounts. The only condition is that you should be using a Gmail or Google Apps email address. In Gmail, you can add a dot (.) anywhere in the username and all emails addressed to the new alias will still reach your mailbox. For example, if your orginial email address is myemail@gmailcom, any emails sent to firstname.lastname@example.org or email@example.com will land in your mailbox because Gmail always ignores periods in the email username.
That is what you can use to trick Twitter. Twitter will consider firstname.lastname@example.org and email@example.com two separate and valid email address even though they point to the same Gmail Inbox. If you think its too good to be true, try it for yourself!
Another workaround: when you open an account in Gmail, you automatically get another valid email address that uses the googlemail.com domain. So if you only have two handles on twitter, you can use the gmail.com address with one handle and the googlemail.com address with the second handle.