Hi,
Yes, 2 stories is absolutely enough.
For others reason this Q&A it's also important to note the following:
1) Much harder than preparing each story is handling the deep-dive from the interviewer. Having your stories ready is table stakes...you really need to practice being flexible answering questions you didn't expect - i.e. what do you do when you don't have a response prepared? (Which will happen)
2) It's not a 1-to-1 relationship between dimension and story. I.e. you don't need 8 stories in total (4 dimensions times 2 stories for each). Rather, a story can be flexible. For example, if I had started a business, I could prepare a story that solves for all 4 dimensions (i.e. I can use this story for all 4 questions). Then, you adjust 20% of the story to highlight different aspects.
For example: I showed entreprenurial drive when I started x company. I led the company to success through x, y, z and had a personal impact on the world through out initiatives a,b,c. These weren't easy initiative, because to make them work we had to solve this big x problem and here's how we did it.
^I can change this story any way I want to emphasize entreprenurial drive, leadership, personal impact, or problem solving, depending on the question!