@rainer-joswig, Thank you for the tip of cl:*print-circle* and the explanation about the problem of modifying a literal. With cl:*print-circle* that is set as t, macroexpand-1 explicitly shows differences between uninterned symbols of the same name. In addition, modifying a literal can be a problem even if compiler optimization is not applied, as a literal is defined as a fixed value which should not be updated while running a program.