I would like to create a macro to subtotal only data that is duplicated.
For instance, the current subtotal function subtotals all lines, even those
with 1 line item. Sorry if this is confusing, maybe the example below will
help:

1 2
2 1
2 1

The current subtotal function, if applied above will do the following:

1 2
1 subtotal 2
2 1
2 1
2 subtotal 2

I would like for it to skip subtotaling if there is only one item and only
do it for duplicate items therefore resulting in:

1 2
2 1
2 1
2 subtotal 2

Any help you can provide is much appreciated.