Well, this really isnít that surprising. I guess the first thing I have to wonder is what you have done to optimize each keyword? Meta tags? Title tag? Body content? Img alts? Etc.
Itís possible that if anyone of these shares similarities across both pages, then they will both come up for keyword search 1.
The next question I have is how long ago did you make changes? Itís possible that they search engine is actually using your cached page, instead of you current one. This would also explain why you arenít coming up at all for the keyword search 2.