Quick question for website testing... maybe you noticed something I saw or know about?

I noticed from a website I came across... how it seemed to flash a different page from the same URL for "split testing".... I guess to test different headlines for sales testing results, to find which headline pulled the most sales.

The website I saw came from a well known marketer online. I can tell he knows his stuff. Just a vibe I got.

Can you help me with this question? Or refer a service or someone that can help me?


you guys rock!