Hi! Welcome to the v58 beta! Thanks for using Dropbox and helping test our beta build!
v58 Release Notes
Desktop Camera Upload was re-importing High Efficiency format photos from iOS devices that had previously been imported via the Dropbox iOS app. This has been fixed.
The splash screen for the first use of Desktop Camera Upload incorrectly showed"Never for This Device" on the opt-out button-- it now correctly shows"Don't Ask Again", reflecting that opting out on the first usage will prevent prompts for any other devices connected in the future.