Software has bugs. If this happens to you (or anyone else), a hard power reset of your mobile phone will clear up the problem. I have not figured out what causes the repeating duplicate alerts. I've asked FEMA and some engineers at a cellular carrier. It seems to be a "known problem." But I haven't been able to get a technical explanation for the cause. The duplication happens randomly on both android and iOS phones, and on multiple carriers. So I'm a bit mystified about the root cause. On Fri, 8 Mar 2019, Jared Mauch wrote:
I’ve had issues with the amber alerts repeating or coming in from adjacent states because “reasons”. When they repeat for days/hours ugh.
I do agree most people have devices. If there is a reasonable API method to fetch them then great.