If, at the return day of any process, it be not returned executed, an alias or other proper process may be issued without waiting (where the first process is returnable to a term) for the subsequent process to be awarded at rules. And where, for want of a return of the first process against a defendant, any subsequent process is issued, if the former was executed, the officer shall not execute the latter, but shall return the former if it be in his possession, and if he has it not, shall return the latter with an indorsement of the execution of the former, and the proceedings thereupon shall be as if the first had been duly returned.