Copying Rows to another Sheet if Unique

[Andrew.Trevayne]

Hello all,
Here again looking for help. I am hoping you can help me with a Macro/Script.
I have 2 Spreadsheets (Listing1 and Listing2).
On regular basis, we update Listing1.
What I need to do is to copy (Entire) Rows from Listing1 to Listing2 if the value in Listing1 (Column C) is unique from that of Listing2.

Any help will be greatly appreciated. I have attached a copy of my Test Spreadsheet.