Off the top of my head I want to say he has CMX8GX3M2A1333C9.
Ask your friend to provide you with the version number of his modules. It will be on the actual label...usually on the bottom line, towards the right side of the label.
This requested info will indicate the manufacturer of the memory chips used to build his modules. If possible, best to match these chips on both pairs so that you reduce the risk of the modules not working together. Or even better, have him send you a pic of the label side of one of the modules. If you could post the pic, then that would also provide the manufacturing date. Even though he doesn't plan on overclocking, having four modules with the same chips, and manufactured near each other will get him close to having a "quad" kit, as opposed to two mismatched pairs of modules. The version number, based on how Corsair's coding works, will also indicate whether the modules are single-sided, or double-sided...another factor which impacts how well they will work together.
While it is very possible that his rig will work with a mismatched set, it will for sure work better if the modules are using the same memory chips, so might as well try that route first.