matrix 1 is most likely regular matrix , also called QS , matrix 2 would be phase matrix , otherwise know as SQ.
most of the quad's put the regular matrix first and the phase matrix second , at the time it was expected that QS
would be the more popular format , didn't work out that way thou , there were way more SQ encoded records pressed
than there were QS , and even less quadradisc (CD4) records made.