diff --git a/examples/cascade_examples/em_shower.cpp b/examples/cascade_examples/em_shower.cpp
index 9316e427d4d21d0ca3aa0eafe5bb9ddabcb66062..138717edc83b3b451691a40dd47b25b00899dd78 100644
--- a/examples/cascade_examples/em_shower.cpp
+++ b/examples/cascade_examples/em_shower.cpp
@@ -184,8 +184,6 @@ int main(int argc, char** argv) {
 
   output.startOfLibrary();
 
-  output.startOfLibrary();
-
   auto const primaryProperties = std::make_tuple(
       beamCode, calculate_kinetic_energy(plab.getNorm(), get_mass(beamCode)),
       plab.normalized(), injectionPos, 0_ns);