I have the link to this post from a couple years ago in reference to multiple workflows starting on the same list item (undesired) but now that I am looking for the same information, I can't find it (after reorg of Nintex Connect).
I do a search on the original problem (a list item is edited once and that kicks of multiple instances of the same workflow) but nothing meaningful comes up.
I suggest you to post again your current question
Here is the original issue I had searched on:
We have SharePoint 2010 and Project Server 2010 (both up to date releases). We have custom content types on the Project Sites within the Project Server site collection and we have applied a Site collection reusable workflow template to those content types. The workflows are set to run when an item is Created or Updated.
In most of the sites (but not all), when an item is updated, two (and sometimes three) workflow instances are created. They run one-after-the-other. We have confirmed that for these sites, there are not multiple instances of the workflows "allowed" (on the Workflow Settings page for the site, the Remove Workflows link).
The original post that I found (mentioned in the title of this post) indicated that there were multiple event listeners that might need to be addressed. Our system admins found a PowerShell script that was supposed to be able to remove the duplicate listeners, but were never able to get it to work. Instead, they had to manually locate and remove the event listeners and since we have hundreds of active projects, that we simply unworkable.
Eventually we modified the workflows so that if they ran more than once they would not cause issues for the users (one part of the workflow as to send notifications), but the still double the workflow load that our system has to handle.
Recently, we've been dealing with lots of system load problems and preventing these duplicate workflow executions is now important again.
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