Using duplicate cell linked data

Hi all

Am struggling with this problem which is eluding me. Your assistance is greatly appreciated.

I have in column C a list of paired duplicate names (text) which can be separated by rows (see John 1) or sequential (see Finn 1) and in column D associated dates. For example say in C3 is the name John 1 (first occurance) and in C7 is John 1 (duplicate).

I would like to write a formula in the cell in column K of the same row of the duplicate ie row 7 which will use the return date value that's in D3 once first occurance of John 1 has been found.

Is this possible?

C................D............K
Milarn 1......12/5/11....
Spencer 1...23/2/11....
John 1........05/1/11....
Finn 1.........31/5/11....
Finn 1.........24/2/11...
Cooper 1.....20/3/11...
John 1.........21/2/11....Formula in this cell to use 05/1/11 eg is 01/1/11 <05/1/11?
Alyiah 1.......10/5/11...

Formula is to appy to all cells in column K where there are entries in column C.

I hope what I have set out is clear and a solution is possible?

Many thanks in anticipation.

Cheers

mgerada