So you want them: - To be at the same temperature. - To be from the same batch of diodes to minimize process variations. - To have equal wiring resistance.
Using both sets of diodes in a bridge (thus probably from the same lot or even on a common chip, certainly on a common heatsink, which tends to equalize the temperature) for ONE phase and soldering the incoming AC line for that phase to the midpoint of a wire running between the two AC terminals of that bridge (to provide a tiny and equal series resistance) tends to do this. Splitting the phases between two different bridges specifically AVOIDS doing this (and tempts you to use different wire lengths, further {and drastically} increasing the imbalance.)[ Parent ]
