sum of all phases of probe_http_duration_seconds greater than probe_duration_seconds

[Cybervedaa c]

From the HELP description of probe_http_duration_seconds:

"Duration of http request by phase, summed over all redirects"

From the HELP description of probe_duration_seconds:

"Returns how long the probe took to complete in seconds"

I would expect that the sum of each "phase" (resolve, connect, tls, processing, transfer) of probe_http_duration_seconds would be less than or equal to probe_duration_seconds.

However when i plot these values side by side, I see that quite often probe_duration_seconds is < sum of phases of probe_http_duration_seconds.

What am i missing? Below is a screenshot of how the data looks when i plot it on grafana. 

Query for panel "Probe Duration" = probe_duration_seconds{instance=~"$instance"}

Query for panel "Probe Duration By Phase" = probe_http_duration_seconds{instance=~"$instance"}

Note also that the panel "Probe Duration By Phase" is stacked

[Cybervedaa c]

Not sure why the screenshot didnt show up in the original post. Attached is the image, showing the graphs.