Hi @Ashley Martin,
First of all, you gave away your tenant's name in your question, for your safety we suggest you edit your question and hide your tenant's name.
Regarding your question, I tested it in my environment and realized that I would only create one item. Usually, multiple project creation is caused by loops in the flow or triggering multiple flows.
We need to run some tests to find the exact cause of the problem:
1.Please close your flow first, and then check if there are duplicate flows that were triggered at the same time and also created items in List B. It is likely that someone in your organization has defined duplicate flow.
2.If this is not the cause of the problem, I would suggest that you look at the run history of your flow and look at the input and output results of each step of the execution and check for exceptions in the run. Just select one of your successful runs.
I suggest you to view it in new view, which has more information. You can also share the details of each step with me (please hide your private information). We can analyze it for you.
3.If neither of the above steps check for a problem, please ask your coworkers try to create the same flow and copy the items to other lists. This step is to confirm whether the problem is with the stream itself or with the list.
4.Try clear your browser's cache and recreate the flow. Check if the same error occurs.
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