Double curtain rod brackets are used when you want to pole in front of the other. Dual clamp is used to hold two rods. You can still use the finials at the ends of both rods and other accessories such as rings, holdbacks, wands and more.
Measured by a two-pole the same as the measure of one rod. Measuring a window or windows, and then decide if you want the bars to extend past the window. If this is the case, decide how much you want to expand the rod. It is your rod length. Then decide if you want finials on both extremes. One popular trend is to use the pieces or something similar behind the bar and use decorative finials in front of the Double curtain rod brackets. Many people put a sheer curtain behind the bar and something decorative and colorful front. Some also want to have a light in front of black-out curtains, so you have many options for lighting in your room. Smaller bars usually look better back in the bar.
Holdbacks are convenient to use, so you can draw the curtains back to reveal the front and possibly the back of the curtains. You can also use the rings in front of curtain rod is easy to navigate. Wands can also help you to move in front of the curtains.
The Double curtain rod brackets may have different estimates. Projection is how far the bars are from the wall. So you can determine how close is in relation to the wall, depending on what you hang curtains and what style you like the room and the window.