The temp problem
I had some problem with my Ender-3 and and found a post describing the problem and solution:
OctoPrint doesn't show a temperature graph for my Creality printer with stock firmware
The plugin solution problems
The solution appoints 2 plugins but unfortunately this fix did not work for everyone and I unfortunately am one of them.
Creality-2x-temperature-reporting-fix not working
Creality Ender 3 V2 Temperature Log - still problems after applying "fix"
Another drawback with the plugin solutions is that the printer will continue with the faulty reporting and the faulty messages will be seen in the "Terminal" tab.
The new firmware solution
The good news is that when I searched for and installed a new Ender-3 firmware I found out that the reporting in the Terminal tab seems fully okay with no double entries etc. so I came to the conclusion that Creality finally has solved the issue 
Entries now looks like:
Recv: T:21.80 /0.00 B:21.13 /0.00 @:0 B@:0
How to get the firmware
The corrected firmware is found at the Creality Software Center pages 3D Printer Slicer Software& Firmware Download - Creality 3D
But ... you might need some help to understand what firmware you need because there are a lot of them. 
Some guidance below:
You might need to know the hardware version of you printer motherboard.
For me it is 4.2.2 so I will check for 4.2.2 in the firmware name.
You might need to know if the motherboard has the STM32 or GD32 chip (Giga device).
For me it is the STM32 chip so I will exclude the firmware with GD in the name.
You have to know if you have the option BLTouch to select the BLTouch firmware or not.
You have to know if you have the "filement detection" device to select the filament detection firmware or not.
For my Ender-3 V2 I used the firmware "Ender-3 V2_Marlin2.0.8_HW_V4.2.2_SW_V1.0.7" dated 11 Aug. 2022 so any firmware for your printer dated around Aug 2022 or later might be corrected.
And the firmware update is not that hard:
You download the correct firmware zip-file, copy the "xxx.bin" file found in the zip-file to an SD-card, insert the SD-card in to your printer and turn on the printer and finally, when possible, check the new firmware version. To check the current firmware version before installing the new one could be a good idea.
See for example https://www.youtube.com/watch?v=Hp5CSx_x9Zg
Note: This clip also shows how to find the HW and Chip versions at an Ender-3.
==Hope this helps::Hope this helps! 