I have created a daily run flow.
Compare records (basing on Italent ID) between a SharePoint list (call A list) and an Excel list (B list), for record exists in B list but doesn't exist in A list, then create the item in A list.
This flow runs for a long time, but recently we found that items were created duplicate in A list, after checking running history but cannot find what's the problem.
@YanLiang i would suggest to design your flow as following to check if excel value exists in SharePoint List. Here i am comparing ID columns from excel and SharePoint you can use whichever column you need to use. The condition checks the length of items returned by filter array is zero then value from excel doesnt exists in SharePoint.
Condition Expression
length(body('Filter_array_2'))
500+