When someone turns into someone else in a dream, it is because there are similar qualities between the two individuals or one person seems to be behaving like the other. Your subconscious sees them as very similar or giving off the same energy.
When something turns into something else, your subconscious is showing you how one thing has lead to another. What changes or transformations have been going on in your world or within yourself lately. Are you able to see how it correlates to what is changing in your dream?
If you are turning around or turning a corner in your dream, ask yourself how things are changing in your real life right now.