No idea. I personally have used identical ram in an upgrade, the only difference was the batch number, and they wouldn't work together. I've also mixed totally different ram and it worked just fine, without needing any adjustments. It's for this reason ppl will tell you that mixing ram is usually a bad idea, since there is no guarantee that it'll work, only a decent chance it'll work with some adjustments, and a slim chance that it'll be perfectly fine. Many ppl get lucky, many don't, and end up returning the new ram and either buying the ram they want in a full kit, or trying something different. Either way, it's a hassle. Meaning, the RMA process of some online companies is not good, can take weeks to get your money back.
If you really want 16Gb, I'd suggest buying a full kit, (2x8Gb sticks), and selling your old ram to get some cash back.