I do not believe that these two temperament inventories measure the same things.  The following exchange illustrates what I mean:

Dear Hal,
My name is Bryne. I have taken both the MBTI and the DISC tests. On the DISC test, I tested as a Mel Phleg; as for the MBTI, i tested as an INFP/INTP(my score for the T/F scale is pretty close). So, how do I reconcile the results of these two tests? Does INFP correlate well with Mel Phleg or does INTP correlate better? Please advise.

and I answer:

I’ve always been interested in trying to reconcile the Myers Briggs and the DiSC; in my observation they are NOT the same way of looking at temperament.

For example; I have a friend who is, like me, an INFP - both of us are rate strong for this type.  However I am a Phlegmatic Choleric (High S, High D) and he is a Phlegmatic Melancholy (High S, High C).

So while we both tend to be laid back, my friend is much more analytical and critical and I am much more results-oriented.  (”Results-oriented” is a relative term in a Phlegmatic!)

Since you are also an INFP we should share some of the same approaches to life HOWEVER because you are Melancholy first and Phlegmatic second, you’re personality would seem to differ from my friends’ and me in many ways.

I realize this isn’t a direct answer but it does indicate to me that the two types of inventory measure different qualities.

Wish I had more; I guess I should put more effort into this but I’m a Phlegmatic so  . . . .

Hal Warfield