We have implemented NPSP in our Salesforce org. We created an Opportunity Trigger to send an email notification and create a task with a PDF attachment after an Opportunity is created. In Sandbox, when we test the trigger, it is only sending 1 email and creating 1 task, however, after deploying it to Production, it is sending 2 emails and creating 2 tasks. 

When we review the debug log, it is actually going through the After Update event before it fires the After Insert event. We verfied that there are no workflows or Process Builders fired before the After Update trigger event. Any idea why the After Update trigger is getting fired before After Insert? It is only doing this in Production, not in Sandbox.