How would this work in practice.
For example, someone who traditionally scores consistently as ENFP begins to have the following preferences in their scores:
Ne > Ni > Fi > Fe > Te > Si > Se > Ti
This indicates that the individual may be developing into an INFJ. Ni is growing stronger than Fi, and Fe is overtaking Te, but Se and Ti are still at the bottom of their preferences.
I.e. sometime I score enfj and sometimes infj in the cognitive function test. And sometimes they or messed up together.
This could follow the same pattern, but could also simply be the result of well developed dominant and secondary functions. Splitting between the Introverted and Extroverted versions of like types is very common for people who are well developed cognitively. People lean more strongly on different functions as needed. Someone who has a well developed Fe and Ni will shift between seeming like an INFJ or an ENFJ depending on which approach to thinking is best suited to adapt to the situation.
However, these leanings could eventually become the norm, and the progression over time may look something like this:
Ni > Fe > Ti > Se > Ne > Fi > Te > Si = INFJ
Fe > Ni > Ti > Se > Fi > Ne > Te > Si = INFJ leaning ENFJ
Fe > Ni > Se > Ti > Fi > Ne > Te > Si = ENFJ leaning INFJ
Fe > Ni > Se > Ti > Fi > Ne > Si > Te = ENFJ
How would you know which one is the new type?
The new type will be the one that emerges through pattern. If there is no emergent pattern, then it is likely that your results simply indicate a balanced development of primary functions, and the discrepancies are simply indicating your current lean of adaptation.
In my experience, it is quite common for ENFJs to test as INFJs when they are leaning introspective to use their inferior Ti function. Leaning on Ti in this manner causes ENFJs to also lean on their secondary Ni, as these are their introspective functions. In order to take cognitive function tests, ENFJs who have good degree of development in Ni and Ti will reflexively lean on them to answer the introspective questions. The end result is a set of scores that often appears to be slightly Introverted, or slightly favoring Ni and Ti over Fe and Se respectively.
A good way to tell the difference would be to inventory yourself with these links.
INFJ
ENFJ
also, you could be somewhat a product of different types thus conflicting scores. how would you know if you are in the process of changing type or not?
The cognitive function model is reactive based on natural pairings. For example, when Ni becomes dominant a secondary judging function will emerge in the form of Fe or Te. Ni never pairs with another Percieving function nor Ti or Fi. If someone has function preferences implying this, then it is likely that they are in a transition or they simply had a poor interaction with the test.