Avoid duplicate posts with xml rpc

I'm new to Wordpress and I'm not a developer. I'm running an IFTT applet that posts a WordPress post each time I upload a new video on my Youtube Channel.

There is a bug with IFTT. It often posts the same post 2 or 3 times.

Therefore, I'd like to avoid duplicates before they are published. I read on forums that I needed to add a XML RPC plugin.

I tried this solution (Set up on Site B) XMLRPC Avoid duplicate content

I added the code using Insert PHP Code Snippet Wordpress plugin.

But it doesn't work for me. I still have duplicate posts coming in.

I also created a plugin file and it doesn't work either.