Well, the tests seem to imply that the T-34s hull and coaxial MGs are better than the PIV's, though it doesn't support the assertion that they differ in the "Focus Fire" property". Perhaps that isnt what you meant, though. (More than just one test would be nice, incidentally)
I have heard before that the T34/76 and t34/85 do have abnormally strong hull/coaxial machine guns, though knowing the exact statistics would be nice. I'm not certain, but haven't the T34s MGs been tweaked in a patch in the last half-year?
T-34/76 2 mgs have around the total DPS of 3 of PzIV, you can find the DPS in https://coh2.serealia.ca/#126
T-34/76 was given better mgs than other tanks to make up for the fact that it was delayed when it was moved to T4 in the 3 building soviet design around 5 year ago.
T-34/85 got the same buff by accident because it was using the same weapon but it was changed making the T-34/85 a very cost efficient tank.
KV-1 had it HMG buffed also a couple of years ago.
(probably because people used in T-34/76 performance where wondering why KV-1 mg are worse)