I would not recommend working with different questionnaires. This will result in three data records per case. Usually, it is much more convenient to randomize the page order, having two blocks to display in varying order.
If you would like to do it that way, then jumpt to the first questionnaire, first:
if (value('RF01') == 1) {
goToQuestionnaire('emo_a');
} elseif (value('RF01') == 2) {
goToQuestionnaire('emo_b');
}
Then, make sure that the respondents return to the parental questionnaire, and then (there, on the next page), jump to the other one:
if (value('RF01') == 1) {
goToQuestionnaire('emo_b');
} elseif (value('RF01') == 2) {
goToQuestionnaire('emo_a');
}