It is not possible to have more than one Instagram account on one device. However, you can create an Instagram stream. To do this, open the following link https://instagram.com/accounts/logout/. This will log you out of your instagram account and allow you o log in to your alternative Instagram account.
I have 5 different accounts on my iPod! Just log out and create an account but it must have an unused email and you can log on your other account sometimes then switch. But once you reach 5 accounts it won't let you.