NAnt - A .NET Build Tool

I am having a problem with a build...

I have a solution that contains two projects. Each of
those projects contain references to .dll's. In order to
facilitate a simplified deployment method, the company
has made the decision to put these .dll's into a folder in
each project. After they are placed in the folder a
reference is then added for that .dll and the reference is
pointed to the .dll within the folder. In one instance
the .dll in question is used in two projects and the same
process of adding to a folder and locally referencing is
repeated in each project.

Within VS.NET 2003 the solution builds fine and there
is no problem with the references.

However when building this solution in NAnt I am
receiving the following error:

error BC30560: 'SqlHelper' is ambiguous in the
namespace 'Microsoft.ApplicationBlocks.Data"

I suspect it has something to do with the conversion
from assembly references to project references, but I
am not sure and have not been able to resolve the issue.

I have included a sample project (scaled down) that
repeats the issue and is representative of what is
happening in the original project.

Thanks...