As I assumed, no it's not a good idea. Nothing I would do.
Q - How did you end up with 1 stick of each from both being 2X__GB Kits?
F3-10600CL9D-4GBNT - http://www.gskill.com/products.php?index=97
F3-12800CL9-4GBXL (is 1 stick of the F3-12800CL9D-8GBXL kit) - http://www.gskill.com/products.php?index=355
DDR3-1333 (667MHz) 9-9-9-24 @ 1.50v
DDR3-1333 (667MHz) 9-9-9-25 @ 1.50v
DDR3-1333 (667MHz) 9-9-9-25 @ 1.50v ; set the DRAM Frequency DDR3-1333 and CAS Timings