Creating short forms for multiple codes

Hi,
I have to combine multiple line items to make one representative single code but for the life of me have not been able to find a way to do it effectively. I have attached a sample file. Please do go through it and let me know if you know of a solution Thanks in advance.

Input:
Multiple Lot #, Code
Lot1, ABC123
Lot1, ABC124
Lot1, ABC145
Lot1, ABC147

Output:
Unique lot number, Single short code
Lot1 - ABC123,4,45,7