When reviewing my system settings before submitting the Valve Hardware Survey I noticed that the refresh rate of the slower monitor got picked instead of the primary one.
The "The primary Display Resolution" is however correct.

Primary Display: 1440p 240 Hz
Secondary: 1200p 60 Hz

From the report:
Monitor Refresh Rate: 59 Hz
...
Primary Display Resolution: 2560 x 1440
Desktop Resolution: 3760x1920
Primary Display Size: 23.62" x 13.78" (27.32" diag)