ESP8266 returns whatever is sent through Arduino serial
I noticed when testing my ESP8266 using the Arduino IDE serial console that ending with a CR repeated what was sent, a NL executed the command and combination of the two yielded a combination of the two behaviours. This could have just been the firmware on mine (it seemed to be non-standard), but it is possible that the behaviour is similar on yours. If you are using CR &amp; NL, it would explain repetition. However, I can't explain commands not executing, or executing abnormally.