Usually double panes are more important in the cold, not in the warmth. A house is typically kept at around 72F. Depending upon where the house is, seeing temps in the negatives is very possible in the winter. That’s a Tdelta of 70 degrees or more. In the summer, your Tdelta is probably not much more than 30 degrees since few places get much higher than 100F or so. The higher the Tdelta, the more heat transfer there will be.
If you have issues with too much heat coming through your windows, then an easy solution to try is tint the windows. Home Depot has window film which you can cut to size and install on any window, including patio doors. The best ones have a reflective coating which bounces the light away from the house. You can install them in just a few minutes and I think most of them are totally removable.
Having shade is incredibly important as well. Planting a tree or bush which will give the window and the side of the house shade will do wonders to cooling a house down. A pergola or other structure that shades the area is an easy solution as well.