The best way to do this is usually with a script. There is an extension that does this: https://support.airtable.com/docs/dedupe-extension. There are also a lot of sample de-duping scripts and some youtube videos on this. (I do not know scripting, and this is one of the few scripts I have in our bases.)

In this case, though, since identifying duplicates is relatively straightforward (which it isn't always), I believe you should also be able to do this with an automation.

The trigger would be "When a form is submitted". Then, the next action would be Find Records based on the ID field of the newly submitted form.

From there, you would add a Conditional Action. If List of Record ID/ Name from Find Record step exists, send an email/slack/etc with links to both the new duplicate and previous record(s).

Hi MLO

Thanks a lot for your reply. 

I've tried to create the Automation now, but for some reason it also sends me an email when there is no duplicate to be found. 

My Automation looks like this (see picture). 

The trigger is 'When a form is submitted' 

1. Action is 'Find Records' Where ID (from the table) contains 'ID' from the form

2. Action (Conditional) is 'If Records List of 'ID' (from Find Records) contains ID (from the form). 

Can you see what causes the issue?

Try the condition: where List of Record IDs is not empty.  

Our miniExtensions form allows you to enforce unique values for certain fields. This way, users would be unable to submit a record containing a duplicate value and instead see an error message.