Align two datasets with same Date and Time

I have four columns as follows:

[------A--------][----B----][-------C-------][---D--- ]
---timestamp-------keyID-------timestamp-----value
9/23/1986 13:30 Ea_Ar_1_0 9/28/2012 16:00 143.97
9/23/1987 13:30 Ea_Bc_1_0 9/28/2012 15:59 143.91
9/23/1988 3:15 MP_Ar_1_0 9/28/2012 15:58 144.045
9/23/1989 18:37 Ea_Ar_4_0 9/28/2012 15:57 144.02
9/23/1990 5:52 Ea_GC_4_0 9/28/2012 15:56 144.08
9/23/1991 5:52 Ea_Ar_31_0 9/28/2012 15:55 144.08
9/22/1992 21:44 Ea_Ar_12_0 9/28/2012 15:54 144.095
9/23/1993 4:14 Ea_Ar_1_0 9/28/2012 15:53 144.12
9/23/1994 12:48 Pl_Ar_1_0 9/28/2012 15:52 144.1
9/23/1995 0:08 Ea_Ar_1_0 9/28/2012 15:51 144.15
9/22/1996 14:54 Ma_Ne_1_0 9/28/2012 15:50 144.25
9/23/1997 9:32 Ea_Ar_1_0 9/28/2012 15:49 144.16

I wish to align the values from column B and D with the same timestamp in order to have timestamp on column A, keyID on column B and value on column C.

Can anyone help me with this task?

note:some of the KeyID occur at same timestamp,for those we could repeat timestamp on next row.