I have a site workflow that is querying a list, and building and HTML table that is sent via an email notification. The issue is two emails will be sent each time the workflow is executed, which is daily. Adding a pause action to the workflow did not provide a solution.
Math Operation (Advance Index):
Presumably that is not the desired behavior then?
I'd suggest checking your schedule, make sure there aren't 2 schedules set by mistake or something like that. This is a site workflow isn't it, so the only thing that can start it is a schedule or another workflow.
After testing the workflow on a separate web application, it executes only one time (the desired behavior). In Central Admin, I noticed there are two timer job definitions (Web Application A, Web Application B). Web Application A is running as expected, and Web Application B is starting multiple instances of site workflows.
This support article suggests deleting the extra timer job, but does not suggest how, or scenarios where multiple web applications exist.