Short answer: No.
Your MBTI personality type does not simply change
MBTI personality types are similar to your physical genetics. If your parents are both short, it is not realistic for you to be taller than 6 feet unless you have a growth disorder. However, unlike the height determined by your parent’s genes, inheritance tend to have no influence on one’s MBTI type.
That being said, the only way your personality type would change would be due to some serious personality disorders.
You are born with a set of 4 cognitive functions: a dominant, auxiliary, tertiary, and inferior function. You wouldn’t suddenly have all these functions inverted and re-ordered because you turned from an INFP into an INFJ. You are either an INFP or an INFJ. Most likely, you have been typed incorrectly either the first or second time. People tend to get different test results because they are unreliable.
Why it seems like your MBTI personality type ‘changes’
Let’s assume that you were answering the MBTI test questions honestly both times, and you simply changed your preferences during the second time you took the test. You’ve simply changed your ‘preferences’, but not your ‘personality’. To be more accurate: you’ve become more self-aware about your preferences.
We will make a hypothetical example assuming that you are a young INFJ in elementary or high school and started to take an MBTI test for the first time:
You are comfortable with your dominant function Introverted Intuition (Ni), but still developing your Extraverted Feeling (Fe).
Since Ni is a perceiving function, you tend to answer the MBTI questions with a more perceiving-preferred point of view because you think that’s what you’re all about.
Getting INFP as result.
Even though the INFP description does not fit you 100%, it is still VERY accurate since INFPs and INFJs are both introverted and Idealist (NF) types. They both share very similar interests and goals in life, even though they work entirely different.
Now you're starting to mature, becoming more self-aware, and maybe started going to college or got a full-time job. As an young adult INFJ, you're gonna take another MBTI test to see if you still have the same result:
You have finished developing your dominant function Introverted Intuition (Ni), and gotten comfortable with your auxiliary function Extraverted Feeling (Fe), you are developing your tertiary function which is Introverted Thinking (Ti).
Since Fe and Ti are judging functions, you became aware that you prefer an organized environment and planning things ahead over doing things last minute and going with the flow.
So you get INFJ as result.
Congratulations! You found your true MBTI personality type for the first time. It is much more accurate than the INFP description. In fact, it can’t be more accurate than this!
…or you’re convinced that your personality type has ‘changed’…
After many years of life experience, you're now a grown adult INFJ. You're married to an ENTP and even have 3 children now. You hear about MBTI again. Because it felt like you've 'changed' from INFP to INFJ before, you're curious if you have changed again like the last time.
You have finished developing your dominant function Introverted Intuition (Ni) and auxiliary function Extraverted Feeling (Fe). You have also gotten quite comfortable with your tertiary function Introverted Thinking (Ti), especially now you’re married to an ENTP who helps you understand logic more than ever.
Because your Ti has helped you to be at the place where you are today, you are very thankful for that, so much, that you’ve started to believe that, unlike what you’ve thought before, logic, might actually be more important that feelings to you.
So this time you’ve scored INTJ as result.
Have you changed again?
Not really. This is precisely why you should not rely on MBTI tests to determine what personality type you are. At this point, you’re a mature INFJ with a well-developed tertiary Ti. Unless of course, you had Te-Fi in the first place. Then you’d have been an INTJ all the time, indeed.