lookup multiple values from 2 different sheets

Hi,

I have data in 2 different sheets but I'm trying to do a vlookup and bring over multiple values from a 2nd sheet. They both have the same PO number.

For example there are 2 tabs in the attachment: "PO Lines" and "Invoice Lines"
I'm trying to bring the invoice number from "Invoice Lines" tab to "PO Lines" tab using the "PO Number and Line" as the look up value but there more then 1 invoice number for some of the PO Number.