acid calcareous soil?!

So I'm going to try to balance my soil Steve Solomon fashion. He recommends an M3 test, unless the soil reacts with vinegar, in which case it is calcareous and needs an ammonium acetate test.

So, my soil has quite a significant "fizz" to it. However, last year I got a modified morgan extractable, which showed the pH as 6.4, slightly acid. A Calcareous soil should be well over seven, by definition. I have not added any lime to the soil.

So do I have a calcareous soil, which needs the acetate test and the calcareous soil work sheet, or an acid soil, which needs the M3 test and the acid soil worksheet?

I would get another soil test from a different lab. That sounds messed up, to me.