diff --git a/roofit/roofitcore/src/RooCmdConfig.cxx b/roofit/roofitcore/src/RooCmdConfig.cxx
index 1b144337f82df..c19a0b21ca418 100644
--- a/roofit/roofitcore/src/RooCmdConfig.cxx
+++ b/roofit/roofitcore/src/RooCmdConfig.cxx
@@ -34,7 +34,7 @@ arguments and dependencies between arguments.
 #include <ROOT/StringUtils.hxx>
 
 #include <iostream>
-
+#include <set>
 
 namespace {
 
@@ -286,18 +286,24 @@ void RooCmdConfig::print() const
   }
 }
 
-
-
 ////////////////////////////////////////////////////////////////////////////////
 /// Process given list with RooCmdArgs
+/// Emit warning if duplicate arguments
 
 bool RooCmdConfig::process(const RooLinkedList& argList)
 {
-  bool ret(false) ;
-  for(auto * arg : static_range_cast<RooCmdArg*>(argList)) {
-    ret |= process(*arg) ;
-  }
-  return ret ;
+   bool ret(false);
+   std::set<std::string> opcodes;
+   for (auto *arg : static_range_cast<RooCmdArg *>(argList)) {
+      auto opc = arg->opcode();
+      if (opc && opcodes.find(opc) != opcodes.end()) {
+         coutW(InputArguments) << _name << " WARNING: argument " << opc << " is duplicated" << std::endl;
+      } else if (opc) {
+         opcodes.insert(opc);
+      }
+      ret |= process(*arg);
+   }
+   return ret;
 }