Twice? I wonder what alarm clock apps decide for this.

GNU date defaults to EDT, but adding the local time zone name can give the other time:

  date --utc --date='TZ="America/New_York" 2025-11-02 01:30:00'
  Sun 02 Nov 2025 05:30:00 UTC
  (Which is 01:30 EDT)

  date --utc --date='TZ="America/New_York" 2025-11-02 01:30:00 EST'
  Sun 02 Nov 2025 06:30:00

although for London it defaults to GMT:

  date --utc --date='TZ="Etc/London" 2025-10-26 01:30:00'
  Sun 26 Oct 2025 01:30:00 UTC

  date --utc --date='TZ="Etc/London" 2025-10-26 01:30:00 BST'
  Sun 26 Oct 2025 00:30:00 BST

It throws an error the other way:

  date --utc --date='TZ="Europe/London" 2025-03-30 01:30:00'
  date: invalid date ‘TZ="Europe/London" 2025-03-30 01:30:00’