Hacker News Reader

Not sure, why these guys are missing basic thing....

While I understand the usual practice is to redirect one to the other, what is the reason they both can't be a valid address?

Having both schemes will lead to duplicate copies on search engines.

This is like the ABC of SEO, BUT there is a robots.txt that may keep those crawlers away..

Apart from SEO, it is also a bad practice. Think of multiple copies spread across many subdomains without any purpose