virtual domain spidering

is this a potential domain duplication problem?

[proxyHunter]

Hi I have one domain as my main ip and a few other sites that are virtual hosted on the same ip.

main domain: www.domain.com

the other domain is

www.abc.com

but this can also be reached if you go to:

www.domain.com/abc

i know if you never link to www.domain.com/abc ,google wont know about it and only know www.abc.com.

but my problem is some else has link to www.domain.com/abc

Will google see the two url as duplicated content?

hope i was clear enough in my explanation.

[ciml]

You could use a /robots.txt file to prevent spidering of www.domain.com/abc but the 'normal' solution would be to use an HTTP status 301 redirect.

Either of these approaches would save bandwidth. There's been much talk of a mysterious 'duplicate content penalty' but I don't believe in it; when Google find identical pages it merges them, giving both sets of backlinks to whichever address remains.

[xlcus]

I would go for the 301 redirect option. Not only will it prevent www.domain.com/abc from appearing, it will also pass on the PR from any links to www.domain.com/abc