Monitor stands come in different sizes, shapes, and mount options. Typically the dual systems are multi-bracket stands as they require more sturdiness to support dual monitors simultaneously.
The first type is the free-standing stands with heavy bases to stand independently without clamping or screws. These are great if you constantly change your work setup.
The second is stands with articulating monitor arms. These are usually used when you require a lot of movement in your stand’s arms. People working in studios generally use them as they can be freestanding or fixed.
The last ones are the fixed bases that are either secured by grommet mounting or via C-clamps. These types of stands can house larger and heavier monitors and be secured to the desk or the wall. However, they require a bit of backend space to function properly.