Just got home from work and caught up with the thread. Now that Mel 22 Sector NX-U d2-31 exists in EDSM I checked the candidates again and it's as good a match as the other ones, replacing the old Mel 22 Sector NX-U d2-33, which I felt was too far away from the expected distances to be reliable match. This doesn't really provide anything new to the discussion as the base on d2-31 was already found.
Code:
Mel 22 Sector ZU-P c5-1
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Merope: 136.58 Ly (+0.019 %)
HIP 14909: 26.94 Ly (+0.007 %)
Col 70 FY-N c21-3: 836.59 Ly (-0.048 %)
Mel 22 Sector NX-U d2-31
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Merope: 125.22 Ly (+0.024 %)
HIP 14909: 26.97 Ly (+0.003 %)
Col 70 FY-N c21-3: 823.40 Ly (-0.033 %)
Mel 22 Sector NX-U d2-27
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Merope: 131.18 Ly (+0.039 %)
HIP 14909: 34.74 Ly (+0.012 %)
Col 70 FY-N c21-3: 816.15 Ly (-0.000 %)
Now what comes to the new audio entries...
My theory is that each one of these will yield a set of unique transmissions.
HIP 14909 transmission yielded distance using Merope, HIP 14909 and Col 70 as the reference and pointed towards the three Mel 22 Sector structures.
Mel 22 D2-31 will yield distances using Merope, Mel 22 D2-31 and Col 70 as the references and will point towards the two remaining Mel 22 Sector structures and the HIP 14909 structure.
Essentially I'd imagine it's a way of "If you found one, here's the coordinates to the other ones."
In any case I'd be interested to verify this theory.