Yes, the etymology is the same (particle に+ particle て). I, either, can't find the thread, though.
~で有名 works almost as a set phrase. For instance, 静かで有名な観光地 can mean both "because of" and "and then", but で requires that the preceding word must be a noun (静かなこと/ので有名 or 静かさで有名), so it's clearly recognized that this で is always the particle, and not the continuous usage of copula. Thus, they are different words in this case.