The earliest reference I can find to the use of felt wads soaked in grease, between the ball and powder, is from Elmer Keith.
The late gun writer (1899 - 1983) wrote that his first sixgun was a Colt 1851 Navy, purchased about 1912. Keith said that the old timers in the Helena, Mont., area showed him how to load it.
At that time, Helena had a lot of Civil War veterans, from both sides, he wrote.
Actually, Keith doesn't specifically note that these veterans told him to use a greased wad but I suspect they did. If they didn't, that would place the practice into the 1920s or 1930s.
I've never seen a reference to the use of a greased wad in the Civil War. Some soldiers are known to have dripped beeswax or candlewax over the loaded bullets and caps but this seems to be more for waterproofing than for lubricating purposes.
As noted above, Colt's makes no mention of a lubricant over the ball or a greased felt wad under it.
Actually, I've never been convinced that multiple discharges result from the flame entering around the ball. I believe they stem from the flame entering around the percussion cap.
In the early 1970s I owned a cheap, brass-framed .44 that discharged multiply on three separate occasions. Each time, the ball was slathered in axle grease.
The first two times didn't damage the gun. The loads on either side of the hammer went off. The third time, the ball in line with the rammer went off and damaged the frame and rammer.
In 1983 I bought a Colt 2nd generation 1851 Navy and have put an estimated 2,000 balls through it. Most of the time, it was loaded with greased, felt wads under the ball. I've never had a multiple discharge with it, or any other cap and ball I've owned.
Aside from poor workmanship or a revolver being worn to the point of danger, I just don't see how a flame or spark can find its way past a tightly fitted ball into the chamber.