lucy24 - 12:21 am on Dec 16, 2013 (gmt 0)
Can't be done. A 301 redirect is, by definition, visible. That's the difference between a redirect and a rewrite. After the redirect has been running for a while, the old URL will drop out of the index.
Now, if you want Site A to show the content of Site B with nobody the wiser, that's a proxy. Whole nother question.
And if you want to show one thing to your competitor and an entirely different thing to a major search engine ... uh ... I think you've come to the wrong forum :(
Edit: A search engine will never show the Redirect response as such. It will show either the new URL or the old one.