Compare Last Names And Dates Of Birth From Two Spreadsheets

I have several old spreadsheets that contain patient information. Except for names, dates of birth, and dates of surgery there is nothing consistent about them. Not only that, the old spreadsheets were in various stages of compiliation and recompilation when they were abandoned. So now there are multiple duplications of old names added to lists of new names spread across multiple spreadsheets. I have to identify names that are not already in my database and add them.

I have a formula that I found on the internet that I can use to check if a patient’s last name in an old spreadsheet is one that already appears in my main database. In my attached example the formula looks like this: