ENH: drop variant modify values if inconsistant

Change-Id: I6c3e487e4b222df63f91aceccff13c3afd002ab8
Jira: none
(cherry picked from commit 9801a10f7f660c25eb5f8269350f126d5facbd6a)

src/slic3r/GUI/Plater.cpp

@@ -763,7 +763,7 @@ void Sidebar::priv::sync_extruder_list()
     for (auto ams : obj->amsList) {
         // Main (first) extruder at right
         if (ams.second->nozzle == 0) ++right;
-        else ++left;
+        else if(ams.second->nozzle == 1) ++left;
     }
     AMSCountPopupWindow::SetAMSCount(0, left, obj->vt_slot.size() > 1);
     AMSCountPopupWindow::SetAMSCount(1, right, 1);