You get one more trigger for each Teysa Karlov you have. So if you have 2 Teysa Karlov, you get 3 triggers.
From the Rulings on the Gatherer page:
1/25/2019 If you somehow control *two Teysas, a creature dying causes abilities to trigger three times, not four. A third Teysa causes abilities to trigger four times, a fourth causes abilities to trigger five times, and so on. This also means that if you control Teysa and cast a second one, an ability that triggers when it dies due to the “legend rule” triggers three times.