The same endpoint may contain several different transformers, some of which might call the same data-source. For example, the endpoint may include a task to send an email, and the email-body and some attachment both require the same data-source. In this case - the data source is used twice within the same request - they both see the same number. The new incremental id is created per request, not per use of the (same) data-source. However, if you use 2 different data-sources, both calling an auto-increment, then 2 different ids will be created.