Overlap between Linear A and Linear B syllabaries is so high that the latter should be considered a refinement of the former, and not a new syllabary:

Minoan Linear A keyboard assignments620

In the keyboard assignments for Linear A syllabograms above, I have indicated where Linear A and Linear B syllabograms (almost) coincide with the tag lb just below and slightly to the right of each LA syllabogram for which the Linear B equivalent is (almost) identical or very similar. As it turns out, in the Linear A syllabary of 54 syllabograms, 48 ! are either (almost) identical or very similar to their Linear B counterparts. This leads me to draw the inexorable conclusion that the Linear B syllabary is not a new syllabary at all, but that it should rather be considered a refinement of the Linear A syllabary. The Linear B syllabary standardized several syllabograms which had first appeared in the Linear A syllabary, and eliminated perhaps as much as 100 ideograms, logograms and ligatures originally found in Linear A, replacing some (but far from all) of the latter by new ideograms, logograms and ligatures (in Linear B). Nevertheless, the high statistical overlap between the Linear A and Linear B syllabaries argues in favour of a single syllabary in evolution. Of the 54 syllabograms in Linear A, 48 are either (almost) identical or very similar to their Linear B counterparts, and of the 61 in Linear B, again 48 fall into the same zone.

So is Linear A a new syllabary, or is it merely a refinement and standardized version of Linear A? You may draw your own conclusions. I have already drawn mine.

The implications of this hypothesis for the further decipherment of Linear A are staggering.