Crystal Reports has a property called 'Suppress If Duplicated' but it only applies to individual fields. Not the entire row. To suppress an entire row, use the PreviousValue() function to compare the current value to the previous record and if they are the same, then suppress it. This prevents dupclicate records from appearing. Here is a sample formula. Put this in the formula workshop button for the Suppress property of the Details section (using your own field names).

{table.accountnum} = PreviousValue({table.accountnum});

 

I actually cover this exact problem in Chapter 8, Advanced Formatting Techniques, of my Crystal Reports Encyclopedia book. You can find out more about my books at Amazon.com or reading the Crystal Reports eBooks online.