Hello, I always get such an error and do not overcome the problem (compiling appinventor/ai_samiaalr55/X_O/Screen1.yail to appinventor.ai_samiaalr55.X_O.Screen1)
(compiling appinventor/ai_samiaalr55/X_O/Screen2.yail to appinventor.ai_samiaalr55.X_O.Screen2)
ERROR: appinventor/ai_samiaalr55/X_O/Screen2.yail line 30: duplicate declaration of 'back'
[GenerateClasses] ERROR: Can't find class file for Screen 'Screen2'
[GenerateClasses] Task errored in 2.434 seconds