Are you asking about vanilla FF7, or are you asking if repeat battles can be implemented in a mod?
There is a tool called "Teleporter And Instant Battle Trainer " that allows you to encounter enemy's by entering there values into the boxes provided, you can get it herehttp://forums.qhimm.com/index.php?topic=10556.msg147430that will allow you to battle emerald/diamond/ruby again if you want to.