They're not exactly the same plant. The "unresolved" question is whether features of "S. incana" which seem to suggest a difference from S. ambigua, such as the down on its leaves which make them look greyer than S. ambigua, are really sufficient to distinguish it as a separate species.
In general on this forum we tend not to correct such "unresolved" species names when people use them and when they are in common use. But here it was a question of giving the "right" name to your plant, which is why Oron followed the strict nomenclatural rules. I'm ashamed to say that I simply didn't check the current taxonomic position!