Questions MLAT altitude and anonymized MLAT flights

When I forwarded the flights from the FA to VRS, I have used the port that has just my signal (30002 AVR), not the MLAT port.
I am receiving MLAT also from adsbexchange and that’s what I have in my VRS as MLAT.
General statement:
ads-b-flight-tracking-f21/multilateration-mlat-data-t39171.html
MLAT and VRS discussed here too:
ads-b-flight-tracking-f21/mlat-data-into-vrs-separate-feed-t38230.html