Why does the basket have one fuserid and the small mail basket has another?

Question

1C-Bitrix

I use a small mailbox. There is a method for getting a basket by fuserId. I output fuserId. He is alone. And in the database in the basket, the order I abandoned earlier under the same user under another fuser. As a result, I can’t set up a mailing list about a forgotten cart, because the list of items forgotten in the cart is not tied up because of this.