Hi - Thanks for the question, the problem here is in the way you are asking SB trigger to handle the message
[ServiceBusTrigger("Topic_CA","Subscription_CA", Connection = "ServiceBusConnectionString_CA",AutoComplete =false)]
This is the problem
AutoComplete =false
There are in effect two modes of operation
(1) the default is the message handed to your function code has a "peek lock" assigned. Depending on how the code finishes, when the function exits the lock is either completed (the message is removed as it's been processed) or the lock is removed so another instance can retry the message processing (for example the function threw an exception)
(2) auto complete - you can opt out of using peek lock and auto-complete BUT if you do this you need to complete the message (or abandon it) manually in code yourself. I suspect you are not doing this. Not doing this means you see the same messages over and over again as they never get removed
Answer is also explained here https://stackoverflow.com/questions/62752905/azure-function-service-bus-trigger-running-multiple-times