Thanks
Okay the problem is you have got into a bit of a muddle with project names and source code.
Both your visual micro projects compile as arduino project but with NO code other then empty setup() and loop()
The Arduino projects compile okay because you have opened them from their correct locations.
Both of the Visual Micro project outputs are for a project name backChatProject and an .ino called backChatProject.ino
In the Arduino Ide they are called backChatProject\backChatPTX\backChatPTX\backChatPTX.ino etc.
So hopefully you an see you are compiling different code in visual studio than in arduino.
I suggest you close all ides. use windows explorer to clean things up.
Have this type of folder structure.
\backChatProjects\backChatPTX\backChatPTX.ino
\backChatProjects\backChatPRX\backChatPRX.ino
Delete all .sln, vcxproj, .vcxprojuser .sla files. Make sure you don't delete your source code.
Open visual studio. Do not open a project
Click file >open >arduino project and open backChatPTX.ino
Then again Click file >open >arduino project and open backChatPRX.ino
You will have a solution containing the two arduino projects
Click the solution node in the solution explorer, then click "file > save as"
Save the solution with a name of your choice in the backChatProjects folder.
After doing this you will get to understand how visual studio projects and solutions work.
Hope that makes sense.