Don't add system object staff at staffIdx = 0

The first staff already gets system objects by default

src/notation/internal/notationparts.cpp

@@ -799,7 +799,7 @@ void NotationParts::moveSystemObjects(const ID& sourceStaffId, const ID& destina
     startEdit(TranslatableString("undoableAction", "Move system markings"));
 
     score()->undo(new mu::engraving::RemoveSystemObjectStaff(srcStaff));
-    if (!score()->isSystemObjectStaff(dstStaff)) {
+    if (!score()->isSystemObjectStaff(dstStaff) && !dstStaffIdx == 0) {
         score()->undo(new mu::engraving::AddSystemObjectStaff(dstStaff));
     }