I've stripped out the second upload behavior to simplify, but yes, they both give the same problem.
ProdImage is the field name used on the original Insert page (created with DataAssist)
On the upload page (created with DataAssist) I have a ProdImage field, set to show the value entered in the db as the initial value and beside it, I have a File Field, named newimage.
The record update behaviour is set to update the record to the value in the ProdImage field
The file upload behaviour, triggered on Update Record, is set to name the file to the value in the ProdImage field.
The user does have the option to manually change the value in the ProdImage field and it does rename the uploaded file, but it adds the extra extension.
As far as I can tell, the only place I have deviated from the Help document is that I did not HIDE the ProdImage field. This is because if the original product was added without an image, the value of the ProdImage field will be blank and I cannot upload a file with no name.
// WA_UploadResult1 Params Start
$WA_UploadResult1_Params = array();
// WA_UploadResult1_1 Start
$WA_UploadResult1_Params["WA_UploadResult1_1"] = array(
'UploadFolder' => "../db_images/",
'FileName' => "".((isset($_POST["ProdImage"]))?$_POST["ProdImage"]:"") ."",
'DefaultFileName' => "",
'ResizeType' => "1",
'ResizeWidth' => "200",
'ResizeHeight' => "300",
'ResizeFillColor' => "#FFFFFF" );
// WA_UploadResult1_1 End
// WA_UploadResult1 Params End?>
WA_DFP_UploadFiles("WA_UploadResult1", "newimage", "0", "", "true", $WA_UploadResult1_Params);