software

I need some help with arranging rows of data.... here is a
simplification of my problem

I have two seperate lists

Z Y X M
A 1 2 B 4 6
B 7 9 A 5 8
C 7 9 D 7 9
D 8 8 C 6 8

I need to merge it so it is like this

Z Y X M
A 1 2 5 8
B 7 9 4 6
C 7 9 6 8
D 8 8 7 9

so that the values of A in the first row merge with the values of A on
the second row of values into one neat row... As you can see the
problem is that the entries in the first list are not in the same order
as the entries in the second list. The second list has twice as many
entries as the first but should have all the same corresponding
entries that the first list does...