Both my autos take the same amount of dmg when adjusted for AoE differences and was using difference frames with vastly different hps. Even if dt for some reason didn't work on pets my non main target autos were still taking more dmg than a lvl 97 cor with none. And the differences can't be just mnd either given that unless it's counting the OD stuff as a buff but seems doubtful since the dmg increase while severe as much as would be expected. Will need more numbers but if anything the dmg seemed to be more along the lines of if the pet -dt was being counted as +dt
As far as unlock or locked should add that either pup or cor are unlocking it as it uses it all the time when I'm using cor and pups. Also the problem with the setup above as mentioned by Byrth is it still uses dmg increasing buffs. One or 2 might not sound so bad from the VE descriptions but trust me it's huge. On normal when I was trying to test dmg forgot to fold the roll 1 time and dmg jumped from 700-800 to 5k from that 1 buff. On D it's even more extreme though I wasn't as careful with recording buffs and dmg the most buffs I ever had was 3 and dmg went over 20k