man, you forget that the "girl" lived in the same lab for 17 years and never had time to socialize with the outside neither exploit her powers, plus she never planned to get out of the lab while jayoon planned everything. plus we can see that jayoon's twin has "feelings", so when someone attacks her friends, she just annihilates them without expection,while jayoon goes straightforward and has straight thinking. u have to stop thinking jayoon and her twin are the same