Multiple entries in a table with different timestamps, how to determine time difference?

Hi all,

I have a simple table that includes two columns; one of timestamps and another with unique IDs. There may be multiple instances of those IDs in that column, each with their own unique timestamp. I am attempting to determine if the IDs show up multiple times, and if so, how do I determine the difference in time between the first and second occurrence of that ID? For example, if an ID occurs 4 times, what is the difference between the 1st and 2nd occurrence?

To put it into perspective, this is to determine response times on incoming emails into an email box. First occurrence of an ID is the initial email received, and second occurrence is the response to the email. So only the first two instances of an ID showing up in the column are important.

Thanks!

If you add a column and use this formula, it will find the second occurrence of ID and show the time since the first occurrence, see attached.

Formula:

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