I have setup app with the call subscription to understand more about the issue. I am trying to repro the issue at my end, so I just want to confirm how I will check if I am getting same call again. Now it is clear.
I have created two subscription one I am check with multiple update(Patch) and the other with just subscription.
I would like you to check one more stuff whenever you got the same call notification, could you please get that call with Id and check for the version in response JSON?
Also if possible can you try deleting the existing subscription and creating a new and try if you are facing issue in that subscription too?
About other forum- This is the right forum to ask question about Teams development, We are looking into your issue and trying repro and resolve it. I will keep you updated. Sorry about the wait but we need to find the exact source of problem and solve it.
Thanks for understanding.