fix(sim): Check for multiple SensitiveVolumes with same name

Both the transport engines and FairRoot allows for registering
multiple nodes with the same volume/same volume name (copy mechanism).
However currently such workflow logs errors in `FairVolumeList::addVolume()`.

The commit reintroduces the check for same volume names in the
`FairModule::AddSensitiveVolume()` function thus preventing
registration of copy volumes.

Fixes the issue FairRootGroup#1595.

fairroot/base/sim/FairModule.cxx

@@ -280,12 +280,14 @@ void FairModule::AddSensitiveVolume(TGeoVolume* vol)
     auto volName = vol->GetName();
     LOG(debug2) << "AddSensitiveVolume " << volName;
 
-    auto addedVol = vList->addVolume(std::make_unique<FairVolume>(volName, fNbOfVolumes));
-    if (!addedVol) {
-        return;
+    if (!vList->findObject(volName)) {
+        auto addedVol = vList->addVolume(std::make_unique<FairVolume>(volName, fNbOfVolumes));
+        if (!addedVol) {
+            return;
+        }
+        ++fNbOfVolumes;
+        RegisterSensitiveVolume(*addedVol);
     }
-    ++fNbOfVolumes;
-    RegisterSensitiveVolume(*addedVol);
 }
 
 FairVolume* FairModule::getFairVolume(FairGeoNode* fN)