Since you’re asking this on a Mendix forum, I assume you are looking for a Mendix answer. Here we go:
- use Excel importer from the AppStore
- import each Excel table separately and import them to the same table using Date and PBNumber as key (not sure if you can use two keyfields, if not, then first in Excel concatenate the values of Date and PBNumber in a new column, say DatePBNumber)
- show the result on a page and add the standard ‘Export to CSV’ function
NB. If you were to ask this on a Excel forum, I would advise you to get creative with VLOOKUP-function, and at the same time warning you about performance problems when a lot of cells have a VLOOKUP-function.