duplicate process id for different process instance

According to the documentation, Process IDs are unique within a given Appian instance.

Does all of your data stem from the same environment, or was any migrated from a different environment? In general, we recommend to use an auto-generated primary key, so issues like this don't arise.

I believe all data has come from the same environment and there hasn't been any data migrated.
The data has carried over from previous released Appian version.
Was there any prior version like 7.x or even 6.x that behaved differently?
Are there any scenarios where Appian would reuse an ID from a process instances that was archived or even deleted from the system?

I see a previous thread from four years ago, where it is indicated that process ids are never reused, which would cover Appian 7.x, but not necessarily Appian 6.x (although it's unlikely that this design paradigm changed in that time).

Process IDs of deleted or archived processes should also never be reused. Is there any manipulation done to the Process ID before it's written as a primary key? Is it stored as text or bigint?

I see a previous thread from four years ago, where it is indicated that process ids are never reused, which would cover Appian 7.x, but not necessarily Appian 6.x (although it's unlikely that this design paradigm changed in that time).

Process IDs of deleted or archived processes should also never be reused. Is there any manipulation done to the Process ID before it's written as a primary key? Is it stored as text or bigint?

it's being saved to a field configured as varchar(12).
This hasn't happened in our production environment, only development and I haven't been able to duplicate it.
My biggest concern was that this workflow is being rebuilt with CDTs and write to DS replacing DB nodes and wanted to make sure this wasn't the cause for the duplicate ID.