Yes, you can have multiple AWS accounts, as long as you're not doing so for bad reasons. According to the AWS Service Terms, "You may not access or use the Services in a way intended to avoid any additional terms, restrictions, or limitations (e.g., establishing multiple AWS accounts in order to receive additional benefits under a Special Pricing Program)" but that's really just a "don't try to cheat" clause.
Prior to the creation of IAM, the standard way of creating restricted-privilege access keys was to have multiple accounts; I have at least 5 AWS accounts (I say "at least" because it's possible I've forgotten some which I'm not using any more...), lots of people at Amazon know about this, and nobody has ever suggested that there is anything wrong with it.
On the other hand, if Amazon decided to close your account, they would probably look to see if there were any other accounts owned by the same person. On the gripping hand, I've never heard about anyone ever having a billing dispute with Amazon Web Services, which at their scale tells me that they're very reasonable people and not prone to Paypalesque random account closing.
Prior to the creation of IAM, the standard way of creating restricted-privilege access keys was to have multiple accounts; I have at least 5 AWS accounts (I say "at least" because it's possible I've forgotten some which I'm not using any more...), lots of people at Amazon know about this, and nobody has ever suggested that there is anything wrong with it.
On the other hand, if Amazon decided to close your account, they would probably look to see if there were any other accounts owned by the same person. On the gripping hand, I've never heard about anyone ever having a billing dispute with Amazon Web Services, which at their scale tells me that they're very reasonable people and not prone to Paypalesque random account closing.