  Some binary mixtures, such as specific alcohol-alkane mixtures, or even
water-tbutanol, exhibit two humps camel back shaped KBI. This is in sharp
contrast with usual KBI of binary mixtures having a single extremum. This
extremum is interpreted as the region of maximum concentration fluctuations,
and usually occurs in binary mixtures presenting appreciable micro-segregation,
and corresponds to where the mixture exhibit a percolation of the two species
domains. In this paper, it is shown that two extrema occur in binary mixtures
when one species forms "meta-particle" aggregates, the latter which act as a
meta-species, and have their own concentration fluctuations, hence their own
KBI extremum. This "meta-extremum" occurs at low concentration of the
aggregate-forming species (such as alcohol in alkane), and is independant of
the other usual extremum observed at mid volume fraction occupancy. These
systems are a good illustration of the concept of the duality between
concentration fluctuations and micro-segregation.
