DDEX Firebird editing queries duplicates columns in Visual Studio 2008

Question

Hello everybody!

I don't know if some of you also has experienced it but when I edit a query in Visual Studio (it uses DDEX 2.0.5 for accessing the Firebird 2.5 database), it duplicates some of the columns. What's really interesting is the fact that only System.Boolean columns are duplicated:

Originally, there was only ,for instance, a 'PRO_DELETED' field...

Now I wanted to sort my results by this field - I had to change the select statement in the so-called QueryBuilder by adding "ORDER BY PRO_DELETED"

...After clicking OK it somehow created a new column (!?) called 'PRO_DELETED1'

My question is: Why does DDEX add such a new row to the column view and why can't I access the original PRO_DELETED field anymore?

Thanks in advance!