May I ask which one is concluded from the original sentence?
There are some actresses who are as famous as Emma, but she was the most famous one who has appeared on the stage. No other famous actresses have appeared on the stage.
The two sentences don't fit together. If Emma is the most famous actress who has appeared there, then other famous actresses have also appeared there - it's just that none of them were more famous than Emma. The second sentence says that all the other actresses who have appeared there are not famous at all.
There are some actresses who are as famous as Emma, but she was the most famous one who has appeared on the stage. Other famous actresses have appeared on the stage, but she was the most famous one.