To ensure that this is created as two separate surfaces, run the CreaseSplitting and select the Enable option before running the ExtrudeCrv command.
-wim
Hello - the file angle tolerance is .001, the polyline segments are ~.7 degrees off,
so Loft does not merge those segments. Extrusions use it’s own tolerance, apparently - if you set useExtrusions to make polysurfaces, you’ll get the same as the loft, or if you set the angle tolerance to 1, the loft will merge the segments.