I answered up there. Trotta is a variation of Trotha, Trothe (the oldest form) ans some others.
It originated a long time ago in Prussia (Today´s Germany). And in the Middle Age, a lot of people didn´t knew how to write, so was not uncommon to write things just by the sound...
Margarethe von Trotta is a famous German writer and there is a man that made bad thing in Namibia too with the same name (I dont remember the full name).
BUT today, Trotta (at least this version) is more common in Italy and Argentina.