diff --git a/src/libslic3r/Model.cpp b/src/libslic3r/Model.cpp
index b3211103df..db0faf269e 100644
--- a/src/libslic3r/Model.cpp
+++ b/src/libslic3r/Model.cpp
@@ -3320,6 +3320,7 @@ void ModelInstance::get_arrange_polygon(void *ap, const Slic3r::DynamicPrintConf
         if (op2 && (extruder_id = op2->getInt()) > 0) ret.extrude_ids.push_back(extruder_id);
     }
 
+    ret.extrude_ids.erase(std::unique(ret.extrude_ids.begin(), ret.extrude_ids.end()), ret.extrude_ids.end());
     if (ret.extrude_ids.empty()) //the default extruder
         ret.extrude_ids.push_back(1);
 }