We have a simple opinion on this: manually hunting duplicates in a 6,000-row spreadsheet is a waste of your time, and you should stop doing it. The user who posted this problem has already done the hard part, they figured out how to flag repeats and assign a unique ID to the first instance. That is real progress. But the remaining gap, propagating that ID to every subsequent duplicate, is exactly the kind of repetitive, error-prone task that modern spreadsheet tools should handle automatically. The fact that they are still doing it by hand, or searching for a macro, tells us the tools they are using have not caught up to their workflow.
Let's be clear about what is happening here. This is not a complex data-science problem. It is a pattern-matching and lookup task that any AI-native spreadsheet could solve in seconds. The user already has a list of numbers, a count of repetitions, and a unique ID for the first occurrence. What they need is a simple rule: for every row where the number matches a previously assigned ID, copy that ID into the row. A formula like `=XLOOKUP` or `=INDEX(MATCH())` can do it, but it requires the user to know those functions and set them up correctly. That is a barrier. The user is not asking for a database migration, they are asking for a smarter spreadsheet that anticipates what they need next.
This is where the conversation about AI in spreadsheets becomes practical rather than theoretical. Instead of asking users to master VBA or write nested formulas, the tool should recognize the pattern. It should see that the user has created an ID column, that some rows are missing that ID, and that the missing IDs can be filled by matching on the seven-digit number. That is not futuristic. That is a straightforward application of pattern recognition and auto-fill logic. The user's time would be better spent analyzing why duplicates exist or cleaning the source data, not copying and pasting IDs row by row.
So here is our concrete take: if you are spending hours on a task like this, the problem is not you, it is the tool. The solution is not a better macro or a database migration next quarter. It is a spreadsheet that learns from what you have already done and finishes the job. Stop manually hunting duplicates. Start using a tool that can see the pattern you have already built and complete it for you.