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This will not compile because A1 and A2 are already declared as aliases for analogue pins 1 and 2
The error message is very explicit
Arduino: 1.5.6-r2 (Windows 7), Board: "Arduino Uno"
sketch_oct31b:1: error: conflicting declaration 'double A1'
C:\Program Files\Arduino\hardware\arduino\avr\variants\standard/pins_arduino.h:50: error: 'A1' has a previous declaration as 'const uint8_t A1'
This report would have more information with
"Show verbose output during compilation"
enabled in File > Preferences.