Removing duplicate entries while preserving their structure

MERGE ROWS
Here's a macro for merging rows of data using the ID in column A and putting the column B values together in a delimited manner of your choosing. There's a sample file as well for testing.

Merge Rows

There's a sample workbook too you could drop your data into and test it out.

Try using a delimiter other than a comma when concatenating all numeric values. Excel thinks it's helping when it restructures numeric strings with commas... use a space or a | and see if it works better for you.

I've tried several delimiters, and to no avail. The output after running the macro is the first row of data, and nothing else. Excel doesn't like the size of the data. For 100,000 rows, I have the same problem. When I run it on 50,000 rows, however, it runs and gives me the right output.

Ah, yes, that makes sense. Even though my macro will eliminate duplicate values, there is a limit to the length of a text string in a single cell, I'm certain of that, though not certain of the effects that has since I've never tested my macro with anything close to that much data.