There are lies, damn lies, and diode datasheets.
Search and look through a range of datasheets on Digi-Key.
Some of the datasheets will show different parameter values at different voltage ratings, such as forward voltage drop, reverse recovery time, surge current, or even thermal resistance. Compare the overall detail of data. Do some have more graphs than others? Is the formatting precise, clear, and consistent? Do some datasheets have an odd similarity to others?
With a series like that invariant values across a wide voltage range could come down to:
- All the parts are actually sorted or binned into a small range and marked at the lowest ranges within the bin
- Worst-case values from the whole series are published, which is easier to maintain across process variations because many parameters don't matter for most applications
- It's actually the same die and is just relabeled
- The manufacturer who introduced the original part set the "standard" and other manufacturers are trying to play "identical specsmanship" in order to get qualified by naive purchasing agents
It's interesting to get a variety and actually test the parts. You could test:
- Does the forward drop vary with actual reverse breakdown voltage?
- Does the junction capacitance vary with actual reverse breakdown voltage?