Hi clay2580,
Welcome to Apple Support Communities. I understand that you're seeing duplicate notifications for most apps on your iPhone. I can see why you'd reach out about this behavior; I'd like to help. If you haven't already, I'd suggest trying these steps first:
If changing notification settings for the affected apps eliminates the issue, I'd suggest doing the same for the remaining affected apps on your device.
If the issue persists after trying these steps, I'd recommend reinstalling iOS 13.4 to your iPhone. First, make sure you have a backup: Back up iPhone
Next, use the steps titled "Place your device in recovery mode and set it up again" in the following resource to reinstall iOS. This process erases the iOS currently installed and replaces it with a fresh copy, so be sure to follow step four closely and choose to "Update" in order to prevent data loss: If you can't update or restore your iPhone, iPad, or iPod touch
Let me know what you find.
Best Regards.