Keep more than the clock label
A local time label such as 02:30 is incomplete without its date and zone context. If a schedule spans a repeated clock hour, two rows can display the same local label while identifying different instants. Deduplicating on the visible hour and title alone can erase an entry.
Consider two invented complete timestamps on the same date, one at 02:30 with offset +0200 and another at 02:30 with offset +0100. Their UTC times are 00:30 and 01:30, one hour apart. This demonstrates offset arithmetic, not the actual clock-change policy of any named country.
Sort by the accepted instant
Preserve each original timestamp and offset, then sort accepted records on a comparable timeline. An alphabetical sort of local clock strings may not represent chronological order when offsets differ.
When presenting the affected interval to a reviewer, include the offset or another clear distinction. A guide screenshot that hides the date and zone can make a correct repeated hour look like an accidental duplicate. The report should make the difference inspectable.
Handle missing context conservatively
If a source supplies only ambiguous local times, the importer needs a documented ambiguity policy or corrected data. Do not guess that the first row belongs to one offset and the next belongs to another merely because that order looks tidy.
Keep any manual resolution with source evidence and the mapping rule used. Recheck adjacent durations after resolving the ambiguity; an interval can become negative or unexpectedly long when converted incorrectly. No real programme time or regional rule is asserted in this example.
Questions answered
Are two entries labelled 02:30 necessarily duplicates?
No. Date and offset can identify distinct instants behind the same visible label.
Does this example establish when a country changes its clocks?
No. It is invented offset arithmetic; current regional rules require their own authoritative source.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.