Hi Al, it of course depends on how the tube is being used in the circuit. If the two sections are cascaded single-ended transconducance amplifiers, or a triode driving a split-load phase inverter, then I'd say the matching matters not at all, so long as each section of the tube is within specs to work for its own part of the circuit.
But for a differential amplifier or cathode-coupled ("long-tailed pair") phase splitter, then the matching of the two sections affects the production of even-ordered distortion products. Both of these types of circuits are sensitive to both quiescent and dynamic balance between the two active elements. The extent to which the circuit can tolerate an imbalance is generally directly linked to its transconductance -- the higher the transconductance, the more critical the balance. It's also wrapped up a bit in the tail current - a true current-source will make the balance less critical for large-signal distortion. One can also place degeneration resistors in the cathodes, and increase the tail current to keep the same transconductance . . . and make the balance less critical.
But for a differential amplifier or cathode-coupled ("long-tailed pair") phase splitter, then the matching of the two sections affects the production of even-ordered distortion products. Both of these types of circuits are sensitive to both quiescent and dynamic balance between the two active elements. The extent to which the circuit can tolerate an imbalance is generally directly linked to its transconductance -- the higher the transconductance, the more critical the balance. It's also wrapped up a bit in the tail current - a true current-source will make the balance less critical for large-signal distortion. One can also place degeneration resistors in the cathodes, and increase the tail current to keep the same transconductance . . . and make the balance less critical.