Spreadsheet Amending 2 pages, 2 columns

Hello - I need a spreadsheet amending with 2 columns worth of data - the data is on the third column but mixed up. The data needs to be separated into the two far left hand columns. There are 2 pages, one is 1175 lines long and the other is 6799. The data is quite often repeated over several lines so you are not filling each column is - shoudl take 3 - 4 hours work Needed to start immediately Thanks Tom