In Crystal, using the grouping features, I don't believe there is. Your best option might be to have the groups in the main report then use a subreport to display all records relating to that group (which would then allow you to show the same record in different groups).
There is one other workaround i can think of but it's pretty nasty. How many groups do you have and are they likely to change?
You could also achieve the same result in SQL returning the "duplicate" records. Are the groups defined in SQL?
L