Have you tried clearing the cache on both apps? Have you tried wiping the cache partition?
That's not was the question was. This isn't about getting a notification reminder later. This was about getting two separate notifications at the same time, not a later reminder. I'm getting two separate notifications from Facebook messenger at the same time in the notification bar. One is a system notification and one is Facebook's notification. This started when I updated my Samsung Galaxy to the new update this month. March
This did start for me only after updating to Android 9.0 Pie also. Actually Android made Samsung get rid of a lot of amazing features such as pop-up window or snap window where you can have two apps open at the same time because you need to do calculations with a calculator and look at your finances in a different window. They also made them change a lots of other stuff which makes the Samsung phone better than the iPhone; if they keep getting rid of it, it's going to be a lame phone just like Apple.
Thank you for your response, but I found out that the problem is solved much more simply.
When I bought my phoneI I used Smart Switch to transfer my apps. After doing so, I wanted to keep some of those apps in the Secure Folder so added them there. This resulted in some apps appearing in the Secure Folder--their app icons had a lock in the lower right corner. However there was still a copy of the app in the regular app folder. When this happens, the S8 acts as if these are different apps and when a message comes in on the app, it's posted twice--once from each app. And it can also have two windows of the app open at the same time.
THE SOLUTION is to go into the main app folder (not the Secure Folder) and uninstall the app. You will be left with only one copy of the app in the Secure Folder.
This is not a proper solution and the problem is not resolved. Please reopen the inquiry!
Have you tried wiping the cache partition of your device?
Here are the steps:
1. Turn off the device.
2. Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
3. When the Android logo displays, release all three keys.
4. An ‘Installing system update’ message will show for 30 – 60 seconds before the Android system recovery menu options appear.
5. Press the Volume down key several times to highlight wipe cache partition.
6. Press the Power key to select.
7. Press the Volume down key to highlight yes, them and press the Power key to select.
8. When the wipe cache partition is complete, Reboot system now is highlighted.
9. Press the Power key to restart the device.
This isn't a solution, but rather a pointer to the bug many of us are experiencing:
For me, I'm getting what sounds like 1 to 3 different notifications for apps like SMS, Whatsapp, and others. Sometimes one is slightly earlier, and one is lower in volume.
I ended up turning down my notifications volume to "vibrate" - but am still getting notification sounds. I think they are coming through the "system" category volume slider.
It started about late May, and I dunno if it's linked to Bluetooth, or my Galaxy watch...
Note 9, Pie, t-mobile.