Question about pronunciation

I watched 'The Nightingale' movie a few years ago. Throughout the movie (which was set in early nineteenth century Van Diemen's Land), the name 'Launceston' was said with 2 syllables (Launce-ston) instead of 3 (Laun-ce-ston) - I'd only heard it with said with 3 syllables until I saw that movie.

What gives? Was there actually a time in the early colony where it was known as the 2 syllable version, or is the movie just wrong? Does everybody there use 3 syllables (like they seem to on the mainland)? Or is there like a contingent of '2 syllables forever' hold-outs who insist on saying it the old way?