Assuming that the two rows have a column that indicates they belong together (like an id field) but then has some other column that can be used to tell them apart (assume a column called Part), then use a self join like this
SELECT T1.ID, T1.otherdata, T2.otherdata_minus_the_data_that_isduplicated
FROM Table1 as T1
JOIN Table1 as T2
ON T1.ID = T2.ID AND T1.Part > T2.Part
David Lundell
Principal Consultant and Trainer
www.mutuallybeneficial.com