- Your system today seems pretty balanced
- Your current sticks are 1.65v, so adding 4 more sticks would be pushing things really hard
- Aside from the voltage concerns, there could be other compatibilities as well with the mis-matched RAM
- Any RAM you purchase now will be throw-away for any future MB/CPU upgrades that you consider; the cutover to DDR4 is pretty much complete for any option you would consider to use for PPro
So, I would suggest skipping this upgrade and savings towards either a further reaching CPU/MB/RAM upgrade or upgrades to your drive(s). You don't mention your drives here, and SSDs are becoming less expensive, faster, and larger, so adding a SSD (or two, or three, or four) might be another way to upgrade your current build and in a way that would benefit any future upgrades or system replacement in the future.
You do not want to mix and match models of ram. The boards do not handle asynchronous timings very well which often leads to problems. Even if you find the same model ram Kingston may have changed the dram chips on the current DIMMs to a different manufacturer than the ones you have. That means they would not work with the current modules anyway. I would plan on replacing all of them and look for 1.35V DDR3 or 1.5V DDR3 if you want to upgrade. If you use AE and Premiere then you definitely want 64GB. You would want 64GB ideally with 4K media as well. Upgrading ram with Adobe is never a bad idea at this point since Adobe uses a massive amount of ram if the system has it available especially with 4K media.