Is there a way to compare two excel files for repetitious cells?

[D. Thompson]

I am trying to find a way to compare two excel files in order to find
duplicate numbers between the two files. I am listing serial numbers and need
to make sure that there are no duplicates listed between more than one Excel
file.

Thanks

[darkwood]

If there was a formula or auto lookup that could do this, I would be very interested as well. The only way I have done this is to create a third sheet and merge the two documents into one,(provided both files have the same format) but color coding one document before merging, and then sorting by the column that I want to look for duplicate values of. This isn't really effective if you have more than 500 rows however, but it gets the job done if you are working with smaller size files.