I do the next SOQL and works:

SELECT FieldString FROM Account GROUP BY FieldString HAVING COUNT(FieldString)>1
  

But when I do the next SOQL doesn't work:

SELECT FieldDouble FROM Account GROUP BY FieldDouble HAVING COUNT(FieldDouble)>1  

Is it possible to make a format change for the SOQL to work? Or is there an alternative to making this SOQL work?