Vlookup question

[slin]

Hi, all,

I need help!

I have Table1 and Table2 in Spreadsheet. In Table2, there are two or more Invoice Number under same Serial Number.
What I wnat is display the Invoice Number as Original Invoice Number in Table1 if Invoice Number in Table2 is different than Invoice Number in Table1 under same Serial Number.
I tried using Vlookup, but it just display the first value found.

Sample data is attached.

Please advise.