成唯識論演祕 3.114

3.114

如一識種色、心兩處皆悉持之，熏既同時，勢力復等。後遇生緣，兩處齊生，故有兩識一時而起。處雖有二，是一識故，名一種也。

For instance, if one bīja of consciousness were held in both places, form and citta: since the perfuming is simultaneous, their potency is also equal. Later, when encountering conditions for arising, they would arise simultaneously in both places; hence two consciousnesses would arise at the same time. Although the locations are two, because it is one consciousness, it is called 'one bīja'.