Associate unique id to other table Dataset Column

Hi,
i wanted to increase the population using the “system” you showed,
Arriving at a point I stopped because I have a problem,
In my DB I have a specialization and generating codes with mockaroo at some point I got a doubt and if it assigns more than one entity to the same id?
I noticed that I can customize the list, I would like to do the type that the first 300 are associated with that entity etc …
I have used several expressions, but I have not had any positive results,
Do you know a remedy or can you advise me something?
Otherwise, I continue to populate by hand.

How Dataset Column no repeats in custom distribution?

Sorry about the disturbance
Good day