If you have a system of four binary indicators, and swapping position on two of the four makes little difference, you probably have a very poor system.
Not to be snarky, but this is spoken like someone who hasn't tried to understand the system at all - not that I believe in it either.
Typically MBTI personality tests measure you based on four indicators: Extraversion/Introversion, Sensing/iNtuition, Thinking/Feeling, Judging/Perceiving
Each combination of indicators is given a "type." There are 16 possible types.
The MBTI personality test also defines 8 cognitive functions, believing that everyone must absorb information (perceiving) and turn it into actions/decisions (judging). It states that there are four ways of perceiving, and four ways of judging... extraverted/introverted sensing/intuition and extraverted/introverted thinking/feeling.
Each personality type has four cognitive functions associated with it: primary, auxiliary, tertiary, and inferior. You will have both an extraverted and introverted perceiving function as well as an extraverted and introverted judging function. Your primary cognitive function will match your introversion/extraversion trait, and then will flip back and forth between introversion/extraversion for the rest of your functions.
Since there are only 8 cognitive functions, and each personality type has 4, it's not surprising that they will often share cognitive functions - it also means that types can behave more similarly than one would expect based on their indicators.
Typically MBTI personality tests measure you based on four indicators: Extraversion/Introversion, Sensing/iNtuition, Thinking/Feeling, Judging/Perceiving
Each combination of indicators is given a "type." There are 16 possible types.
The MBTI personality test also defines 8 cognitive functions, believing that everyone must absorb information (perceiving) and turn it into actions/decisions (judging). It states that there are four ways of perceiving, and four ways of judging... extraverted/introverted sensing/intuition and extraverted/introverted thinking/feeling.
Each personality type has four cognitive functions associated with it: primary, auxiliary, tertiary, and inferior. You will have both an extraverted and introverted perceiving function as well as an extraverted and introverted judging function. Your primary cognitive function will match your introversion/extraversion trait, and then will flip back and forth between introversion/extraversion for the rest of your functions.
Since there are only 8 cognitive functions, and each personality type has 4, it's not surprising that they will often share cognitive functions - it also means that types can behave more similarly than one would expect based on their indicators.