Prevent Duplicate Entries

Hi All,

New here, I wanna do a "Prevent Duplicate Entries" into my column i try the following:

1. http://www.mrexcel.com/articles/prev...duplicates.php
2. http://www.theexceladdict.com/_t/t040818.htm

They all work well but if I'm using copy and paste It doesn't work! why is tat so?

Second issue will be i'm wanna do prevent duplication for the whole column not just one cell. Anyone can help with this 2 problem??

Thanks alot in adv and for even reading!