Hi,
It sounds like you configured /mojoportal as a virtual directory, so even the first site must be http://localhost/mojoportal not http://localhost
If you point the root of the Default Web Site to the mojoportal folder then you can use http://localhost and the other host name as root level sites.
But if you have the first site at http://localhost/mojoportal, then of course it will need the same structure for any other host name since mojoportal is locatedin a virtual directory instead of the root.
Hope it helps,
Joe