Gatling fails on jenkins when run multiple job on multiple executor

Question

I'm using gatling version 2.1.6 with jenkins plugins annd without maven, my scenario are launch with execute shell

#!/bin/bash
if [ ! -f "novapostme/jenkins/${JOB_NAME}.scala" ]; then
  exit 1
fi

${GATLING_HOME}/bin/gatling.sh -df ${WORKSPACE}/novapostme/datas -rf ${WORKSPACE} -sf ${WORKSPACE} -s ${JOB_NAME}

Is each job is run alone on onlly one executor (useing blocking jobs options) all is working well, but when I run multiple job on executors I have sometimes this type of error

[workspace] $ /bin/bash /tmp/hudson6410661655551326741.sh
GATLING_HOME is set to /opt/gatling-charts-highcharts-2.1.6
Exception in thread "main" java.lang.NoClassDefFoundError: MeDocumentDownload
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at io.gatling.app.classloader.FileSystemBackedClassLoader.findClass(FileSystemBackedClassLoader.scala:71)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at io.gatling.app.classloader.SimulationClassLoader$$anonfun$simulationClasses$1.applyOrElse(SimulationClassLoader.scala:57)
    at io.gatling.app.classloader.SimulationClassLoader$$anonfun$simulationClasses$1.applyOrElse(SimulationClassLoader.scala:57)
    at scala.collection.immutable.List.collect(List.scala:303)
    at io.gatling.app.classloader.SimulationClassLoader.simulationClasses(SimulationClassLoader.scala:57)
    at io.gatling.app.Gatling.loadSimulations(Gatling.scala:92)
    at io.gatling.app.Gatling.start(Gatling.scala:70)
    at io.gatling.app.Gatling$.fromArgs(Gatling.scala:59)
    at io.gatling.app.Gatling$.main(Gatling.scala:44)
    at io.gatling.app.Gatling.main(Gatling.scala)
Caused by: java.lang.ClassNotFoundException: MeDocumentDownload
    at io.gatling.app.classloader.FileSystemBackedClassLoader.findClass(FileSystemBackedClassLoader.scala:70)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    ... 14 more
Build step 'Execute shell' marked build as failure
Build step 'Groovy Postbuild' marked build as failure
Archiving Gatling reports...
No newer Gatling reports to archive.
Finished: FAILURE

The question is : is it possible to run simultaneous jobs on mutiple executor ?