find same day shipments

we have customers with multiple sub accounts and I'd need to see if these sub accounts had same day shipments (to consolidate these shipments into 1 and save on freight charges).

I have a Shipment table that shows history of all order shipments:

Customer Acct#, Customer Sub Acct#, Customer Sub Acct#, Order shipment date, Order#

I'm trying to write a query to join this table to itself to compare Order shipment date

select * from Shipment S1 inner join Shipment S2

on Customer Acct#.S1=Customer Acct#.S2  --same master Customer acct

and S1.Order shipment date=S2.Order shipment date --same shipment date

and S1.Order#<>S2.Order#  -- exclude duplications on Order#

and S1.Customer Sub Acct#<>S2.Customer Sub Acct# -- exclude duplications on Customer Sub Acct# as I need to find shipments from different Customer Sub Acct within one "Master" Customer Acct#.

BUT I'm getting duplicated /triplicated records  like reversed info, like this output  for a single "Master" Customer Acct#.

 S1.Customer Sub Acct#  S2.Customer Sub Acct#   S1.Order#    S2.Order# S1.Order shipment date  S2.Order shipment date

            123                                789                          100             200                 1/1/2014                1/1/2014

            789                                123                          200            100                  1/1/2014                1/1/2014

How to limit the output to 1 top line?