Prometheus deduplication

Documentation on Prometheus data source mentions a “dedup” custom query parameter, but I can’t find any detail in Prometheus documentation.
I tried dedup=true, dedup=1 and dedup=exact, but it doesn’t seem to change the results.

Did anyone managed to successfully deduplicate a Prometheus time serie with this kind of custom query parameter ?

The docs referring to dedup were added in this PR: Prometheus: Custom query parameters string for Thanos downsampling by seuf · Pull Request #19121 · grafana/grafana · GitHub

This was to add support for some Thanos specific parameters: Extra settings for the Prometheus datasource when used for Thanos or other LTS solutions · Issue #16665 · grafana/grafana · GitHub

So seems to be referring to the Thanos querier: Thanos - Highly available Prometheus setup with long term storage capabilities