Removing duplicates but leaving values if from another sequence

[ttony123]

Hi,

I need some help with excel as I have a large set of data that is about 900 different values and I want to filter them and have all duplicates removed if they repeat in a single sequnce of numbers e.g delete the two twelves before the 14 if I have 12/12/12/14/14/12/12 and then delete the second 14 and also delete the last twelve as it's a different sequnce so it becomes ===>12/14/12. I could do that manually but since I have 900 numbers it will take a lot of time and I'm pretty sure there is a way of making a short-cut in excel. Thanks

[tim201110]

=if(index($b$1:b2,aggregate(14,6,row($a$2:a2)/($b$2:b2<>""),1))=a3,"",a3)