Get a 2x8GB kit for your Ryzen 2600.

Yes. Sell the 2x4GB and buy a single 2x8GB kit running 3200 or higher. That’s the safest path to 16GB that actually runs at full speed.

The Ryzen 2600’s memory controller isn’t great with four sticks. Running 4x4GB at 3200MHz is possible but far from guaranteed—you might have to drop to 2933 or lower to stay stable. And mixing kits (even same model) is a gamble. The new DDR4 standard is mature enough that a fresh 2x8GB kit from a reputable brand (G.Skill, Crucial, Corsair) will almost certainly hit 3200 without headaches.

Plus, 2x8GB leaves you room to upgrade later to 32GB if you ever need it. With 4x4GB you’re stuck.

Future You with the working memory kit will owe you one.