Hi,
Thanks for reaching out to Microsoft Q&A.
Are you sure the cause of event trigger (placing a blob in container in a specific virtual directory) happened only once?
There's a nice answer from 'Mayank bargal' in the below link (it is for email trigger but both involve azure function multiple triggering issue) which analyzes all the combinations that would cause multiple triggers, please go through.
Please Upvote and Accept as answer if the reply was helpful, this will be benefitting the other community members who go through the same issue.