DDSim crashes when GPS use more than 1 source at once

[atolosadelgado]

• Package version: 1.21, local installation
• short description: I was trying to run GPS, which allows to define several sources of primaries. It seems to work when only 1 source is called to generate primaries, but if all sources are fired at once when this command is added /gps/source/multiplevertex true, ddsim explodes.
• Steps to reproduce the error:

git clone -b ddsim_bug_gps git@github.com:atolosadelgado/dd4hep_cube.git
cd dd4hep_cube
cmake -B build -S . -D CMAKE_INSTALL_PREFIX=install -DCMAKE_BUILD_TYPE=Release
cmake --build build -j 8 -- install
export LD_LIBRARY_PATH=$PWD/install/lib:$LD_LIBRARY_PATH
ddsim --compactFile ./compact/simple_detector.xml --runType run --enableG4GPS --macroFile test34.mac 

The macro file contain the definition of 2 sources of primaries, copypasted from geant4/share/Geant4-11.0.2/examples/extended/eventgenerator/exgps/macros/test34.mac

ddsim throws the following exception:

GenerationInit   INFO  +++ Initializing event 1. Within run:0 event 1.
Geant4PrimaryEvent ERROR +++ Interaction with ID '3' exists and cannot be added twice!
Geant4Kernel     FATAL +++ Exception while simulating:Geant4PrimaryEvent: +++ Interaction with ID '3' exists and cannot be added twice!
Geant4Kernel     INFO  ++ Terminate Geant4 and delete associated actions.
DDSim            INFO DDSim            INFO  Total Time:   4.28 s (User), 0.24 s (System)

Let me know if I can help further on this issue.