Hello gues1,
The NI 6552 allows you to individually program your output low voltage and output high voltage. Technically, you are able to set the low voltage to 2 V and the high voltage to 3.3 V. Then, one channel may output a logical low (2 V), and another may simultaneously output a logical high (3.3 V).
If, however, you would like to simultaneoulsy generate 0 V -> 3.3V logic on one channel and 0 V --> 2V logic on another channel, that would require 3 different voltage settings (0, 2, 3.3), which is not possible.
Does that answer your question?