parse dropdown lists

Question

I have my form made and data being pulled into the dropdownlists. Now I would like to go thru dropdownlists and search for data that might be different and highlight it for the user. I have about 30 in the form so I need this to be compact/modular. More specifically for an example: I have a dropdownlist that lists all the names for a product found in the database, they should be the same, but if they arent I would like to put a star next to the dropdown so the user should look at it and choose the correct answer for submitting. So I should set a label next to the pulldown that I can fill with a *, but how should I go thru the dropdowns to compare the data?