iPhone Quantity Limits

I tried ordering two Iphone 5S, but then my order was canceled and I receieved an email saying:

Dear Apple Customer,

Thank you for your recent iPhone order at the Apple Online Store.

While we appreciate your interest in the iPhone, Apple is unable to fulfill orders that exceed the quantity limit per customer.

Your iPhone order has been cancelled, and you will not be charged.

Thank you for shopping with Apple.

Sincerely,

Apple Online Store Team

So I went ahead and ordered again, but only one phone however, I received the same email.

Don't know really what went wrong here?

I appreciate your help.