问React-native按钮按下可执行3次Firebase数据库更新中的2次

EN

<Button
        title='Up'
        color='green'
        onPress={() => recordUpVote(this.state.currentUser, 'AMZN')}
      />

function recordUpVote(user, instr){
  var today = moment().format('MMDDYYYY');

firebase.database().ref('/votes/' +today+ '/' +instr+ '/voters').push({
  user: user.id  // THIS IS NOT EXECUTING... or is being overwritten..?
    }).then(()=>{
     firebase.database().ref('/users/'+user.uid+ '/votes/' + today+ '/').push({
       instrument: instr,
       vote: 'up'
 }).then(()=>{
       firebase.database().ref('/votes/' +today+ '/' +instr+ '/upVotes').transaction(function(upVotes) {
         return upVotes + 1
       });
     });
});

} // end recordUpVote