Page Visits Funnel (Data Analyst)

Just working on the Page Visits Funnel in python
https://www.codecademy.com/paths/data-analyst/tracks/dscp-data-manipulation-with-pandas/modules/dscp-multiple-tables-in-pandas/projects/multi-tables-proj

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

Thanks