i guess it is working as intended as they intended to cheap out and put them both on a single string.
i guess you could ask them what efficiency lost is or what they designed it to do?
it sounds like it works and not the end of the world. but your looking at a loss of probably 2-10%
now knowing how they are stringed i’m guessing:
MPPT1 is your East and West as your panels are rated just under 6 amps so the only way you can get more than 6 amps is to put them in parallel ie east/west. being only 6 panels your only going to get a max of 327v
MPPT2 is north and being 8 panels you will max out at just under 6 amps and have a higher voltage of 437v
so your volts and amps aren’t really comparable to each other
your DC volts don’t really mean too much as my West have nearly the same volts as my North (same amount of panels in string) early in the morning. while still shaded
Your MPPT1 seems to outperform MPPT2 basically all day so its working ok.
probably not the best but with that roof its probably a half decent install.
If you can compare your system against others with a similar system size you will know how good or bad it is.
if you are using the extra power in the morning and night then its probably worth the loss.
ideally all on the north would be best
i have 20 panels on the west and 10 on the north and the west is only doing 140% of the north. (in winter)