I have owned this site for over 14 months now and I was never the person that implemented this, but in any case.
I have my main domain and it does fairly pathetic in Google, although a PR 5 with lots of backlinks. I also have a 2nd domain name that is pointing to the site when I purchased it. It seems to be an old linux domain name that I guess the previous owner had and for some reason pointed it to a Hip Hop Jewelry site. In any case, it gets 95% of my Google rankings instead of my main domain. It is just a normal redirect through registerfly, nothing fancy.
Even though I optimize a keyword for a page like domain.com/12345.html it will only show the actual domain, no subpages in google even when someone searches for my keyword and it really should show the full url. It is almost like if I fully optimize the page domain.com/12345.html I will rank extremely well for that keyword but my second domain is what gets indexed(yet forwards to main sites index page), yet I know it is because of my optimizing domain.com/12345.html. I have never advertised this domain name myself, I always advertise my main one only.
Of course, I want my main domain to receive all the rankings, I couldn't care less about this 2nd domain name, but I am scared to just throw a 301 redirect up. I understand 301 redirects pass PR and backlinks, but why mess with a good thing? How could I be sure that if my main domain gets 5% of rankings and my 2nd domain gets 95%, if I throw a 301 redirect will I still be getting 100%?
The domain names never share rankings for the same keyword, so it is almost like Google will rank one of the other. I just want them to rank my main domain only, but still not lose my current rankings.
What should I do in this situation? Should I use 301 redirect to tell the search engines to only rank main domain?
It is of course in my best interest for all of my search engine rankings to be under my main domain as people are a lot more apt to click a domain that says hip-hop-realated-domain.com as opposed to unrealated-linux-domain.com if they are searching for Hip Hop Jewelry.