examples/Esp8266/HelloWorld.ino is a duplicate of examples/Esp8266/Esp8266.ino. When a sketch folder contains two .ino files, the Arduino IDE concatenates them before compiling. The duplicate file serves no purpose and causes compilation to fail with redefinition errors.
examples/Esp8266/HelloWorld.ino is a duplicate of examples/Esp8266/Esp8266.ino. When a sketch folder contains two .ino files, the Arduino IDE concatenates them before compiling. The duplicate file serves no purpose and causes compilation to fail with redefinition errors.