In Appendix D, the stat block of Ezmerelda d'Avenir can be found (p. 231), along with the following text:
Tarokka Deck. Ezmerelda keeps a deck of tarokka cards in her wagon (chapter 11, area Vl). Although the cards aren't magical, Ezmerelda can use them to perform a card reading for the characters (see chapter 1), like the one that can be performed by Madam Eva.
There is also this in chapter 1 (p. 12):
At some point during the adventure, the characters are likely to meet Madam Eva, the old Vistani seer (see chapter 2, area G), who can perform the same card reading for them. Characters can also have Ezmerelda d'Avenir perform a card reading for them, provided she has her deck of tarokka cards. Ezmerelda's cards are hidden in her wagon (chapter 11, area Vl).
Given that it is likely that the party would have found Madam Eva long before they find Ezmerelda, is this just here in case the party don't meet Madam Eva, or is there any reason why a second card reading would be useful to them?