Description:
When creating or editing a database entry that includes multiple date fields—such as a "Start Date" and an "End Date"—Moodle does not allow the user to set these dates independently. Changing one date field automatically changes the other to the same value. This behavior makes it impossible to define different start and end dates, which is essential for many use cases.

Steps to Reproduce:

1. Create a database activity in a Moodle course.

1. Add two date fields to the database: e.g., "Start Date" and "End Date".

1. Add or edit a database entry.

1. Attempt to select different values for "Start Date" and "End Date".

Expected Behavior:
Each date field should be independently editable. Changing one should not affect the other.

Actual Behavior:
Setting a date in one field causes the other date field to mirror the same value.