Remember, your personal statement is 'personal' in nature so it is in your best interest to be sure that all the information you provide is in fact your information. By starting with one sample and taking some ideas, then moving on to another and taking additional ideas, and so on, you allow your true self to come out in the finished product and this will give you the best shot at gaining access to the school of your choice.
Just as a strong personal statement can get you in, a poor personal statement/essay can quickly eliminate you from the mix. When a medical school committee has a few hundred applicants, seeing typos, spelling mistakes or bad content will quickly move you to the bottom of the pile. The personal statement is a quick way to "weed out" similar applicants. With two similar applications, the personal statement can decide who gets an interview and who does not.