Conditional formatting duplicates across multiple sheets

I am trying to write a formula in conditional formatting that will identify duplicate values, only the sequential entrie not the first entrie. And I need it to do it across multiple sheets in the work book, the values are in the same column in each sheet.

can anyome help??????

Lo there,

Upload a sample workbook (with sample data) with what you have just now and also manually putting in what you want the result to be.

Cheers

What I am trying to do is keep from entering duplicate number values in any of the work sheets and there are like 12 of them. I dont want the values to be able to be cut and pasted in either, that is probably the biggest threat to the data integrity.

I dont know if Data validation can work or will I have to create a crazy fromula for this to work?

Sample would be great

so here is the file below, Colum "A" is the one with the header "USN #"
is the one I want to keep from multiple numbers being entered across all the sheets. I need is so that if the duplicate value is either typed in or cut and pasted the user will get an error code.

Hope some one can help!

There is a password on it.