Indicate that a field is different than a previous record
I have a flat database and associated form where, among other data, the user fills out his address. I also have a question as to whether the person's address changed since their last entry. Frustratingly, my users can't figure out how to fill out the "has your address changed" question accurately. I would like to add a hidden admin field that I can include in a report view that looks at the address the person enters, compares it to all the previous records, to see if the address was there previously. While not 100% accurate, this could indicate that the address is new. Note that for the vast majority, my users don't share addresses or move into each other's homes.
If you can tell me how to do the above or have an alternate approach, I'd appreciate your input. Thank you.