What source are you using? Nothing I've seen corroborates any of that information, even the split in designation into "A" and "B" -- so perhaps the first LT 1200A is the early version (that doesn't even have the right 1200kg weight) and the 1200B is the one everyone calls "LT 1200".
Here's Lesta Wiki's information:
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And Campbell's "Naval Weapons of World War Two" (not necessarily the best source due to its age):
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German Wikipedia says a few sentences:
de.wikipedia.org
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