I’m no expert, but I’d have thought that was if you weren’t asked to produce at the stop/incident, but then for some reason they asked you later to do so. Generally I guess these would be the same, hence the (if different) part.
Since you can produce within a certain number of days, it would be a bit anal of them to ask you to specify the date AND time you were going to walk into the nick!
Someone else will probably know for definite though
A routine stop and your issued with only the incident date/time completed, this means your seven days starts from midnight from the time of incident.
However, the time of requirement is often used , for instance, if someone is hurt in an accident and taken to hospital…the investigating officer , for whatever reason, can’t see you until the next day…he then fills in the Time of requirement…your seven days then starts from the requirement.
In other words if BOTH boxes are completed the second part (requirement to produce) is the date you go by!