Submitted by: pablo santos (psantosl)

On FbDataReader.cs, line ~377:
for (int i = 0; i < this.fields.Count; i++)
{
columnsIndexes.Add(this.fields[i].Alias.ToUpper(), i);
}

The error shows up when trying to run a sql like:
select table1.field, table2.field

On such cases fields[i].Alias is "field" for both items. This causes
the dictionary columnsIndexes to throw the "duplicate key" error.

Maybe a solution is to concatenate Alias and Relation?
columnsIndexes.Add(this.fields[i].Relation.ToUpper()
+"."+this.fields[i].Alias.ToUpper(), i);

As a side note, ToUpper() can be removed if columnsIndexes is
instantiated using StringComparer.CurrentCultureIgnoreCase.

Commits: 3e1861e