Uma takes birth in different forms

विष्णुब्रह्मकृतशिवप्रार्थनावर्णनं नाम षोडशोऽध्यायः

Vishnu and Brahma's prayer to Shiva - Chapter 16

ब्रह्मोवाच

Brahma said (to Shiva)

उमा सा भिन्नरूपेण संजाता कार्यसाधिनी |
सरस्वती तथा लक्ष्मी द्विधारुपा पुरा प्रभो || 47 ||

God, that Uma is born in different forms to serve purposes, as Saraswati and Lakshmi in two forms in the past.