No, it's not a dumb question. Anyone with any interest in double rifles has probably entertained the same thought. I know that I toyed with the idea for a few years (!) before I lucked into an excellent-condition Baikal SxS 12 gauge coach gun with exposed hammers. A pair of cheapo plastic-bodied fibre optic sights, intended for a turkey gun, quickly found their way onto the rib, attached using only the two-sided adhesive tape with which they were supplied. Voila....a SxS which can be used with X-Full turkey chokes (printing both barrels close enough together at any reasonable range that the patterns are identical in size and position). When cylinder choke tubes are installed, it prints buckshot loads whose centres are usually within four inches of one another, depending on the load used. Best of all, with some (certainly not all) slug loads, it produces a single group of less than six inches at 75 yards. Challenger slugs in particular print so well that the groups from the two barrels are completely superimposed upon one another. It's one of the most interesting and satisfying DIY gun projects I've ever involved myself with.
Here's the big catch...moving the rear or front sight in order to sight in the gun not only moves the location of the impact point, but also alters the relative position of the impact points of the two barrels. Two slugs that hit five inches apart, with the center of the group, say, a foot left, may wind up eight inches apart but perfectly centered when the rear sight is adjusted in the conventional direction. This is very hard to predict, but becomes less so as you spend the time to experiment. But hey, the project is a cheap one, especially if you start to reload your own slugs (something I have yet to do).
I hope to soon replace the plastic sights with a metal, fully-adjustable set, now that I know that the potential for a useful combination definitely exists.
It always helps to be aware of what the conventional wisdom states (i.e. in this case, it states that you are wasting your time and are doomed to failure

) but it never hurts to experiment and try new ideas. I would also caution that some SxS guns have barrels that point in totally different directions, easily seen when looking down the tubes with the gun broken open. I took pains to locate a specimen which, when "bore-sighted" in this crude fashion, seemed to look more or less at the same point with both sides.
By all means play with the idea. Good luck and keep us all posted.
John