SEO question server alias

[wmuser]

I have a page domain.com/page and subdomain subdomain.domain.com
subdomain.domain.com is set to be an alias for domain.com/page so once you visit
subdomain.domain.com you will see exact content as you would seen at domain.com/page
The links etc are all aliased so subdomain.domain.com/file1 is the same as domain.com/page/file1

I am wondering if Google may ban one of pages for duplicate content?
is it a good idea to set subdomain.domain.com to forward to domain.com/page or be an alias but the different way (once you visit subdomain.domain.com you will see the exact content of domain.com/page but once you clcik any link you will go to domain.com/page/somelink)?

[tedster]

I would do it in the reverse direction -- use a 301 redirect www.example.com/subdirectory >> subdomain.example.com. I assume you went to the trouble of establishing subdirectories for a good reason, so those would be the urls you want Google to index.

But however you do it, your basic impulse is right on the money -- do not have two different urls that give a 200 server header for the same content