Yes it does matter. The sliding door and opposite side windows are slightly different sizes, we do not stock windows for right side twin sliding door vans. The normal right side windows will fit the space but the hole is smaller in a sliding door so you may see a small amount of metal edge through the glass when you look in from outside.
If you look at your van on the inside you'll see the single skin metal area where the windows go. This is the aperture you'll look through when the windows are fitted.
You will see that the opening is smaller on a sliding door panel than on a normal wall panel - our windows are painted around the edges to hide all the metal and leave only the opening aperture clear.
We do now stock windows specifically for left and right sides of the van with or without a sliding door. Just be careful when ordering to read the full description.