Page Visits Funnel (Data Analyst)

Just working on the Page Visits Funnel in python

The length of Visits is 2000
The length when all for data frames are merged is 2372 based on solution

all_data = visits\

.merge(cart, how='left')\

.merge(checkout, how='left')\

.merge(purchase, how='left')

Is this because a user may put multiple stuff in the cart? If so it would be good if this was made clear in the exercise