[processing] do not export sdat files provided as part of a multiple raster input

fixes #22131

Author: volaya

python/plugins/processing/algs/saga/SagaAlgorithm.py

@@ -225,7 +225,7 @@ def processAlgorithm(self, parameters, context, feedback):
                     for i, layer in enumerate(layers):
                         if layer.source().lower().endswith('sdat'):
                             files.append(layer.source()[:-4] + 'sgrd')
-                        if layer.source().lower().endswith('sgrd'):
+                        elif layer.source().lower().endswith('sgrd'):
                             files.append(layer.source())
                         else:
                             exportCommand = self.exportRasterLayer(param.name(), layer)