Lookup Data in One Column, Find Multiple Entries in Next, Copy to Multiple Columns

Hello,

I have a large data file I need to process. I need to lookup values in column A (which repeat), and find their corresponding unique values in column B, and for each unique item found in B, copy it to C (item 1), D (item 2), E (item 3), etc.

It's a little difficult to explain so I am attaching a basic sample of a before and after file.
I appreciate any help; I'm stumped.

Thank you