Yes, but
What has been said so far is very true. Grip is very important on these big guns. However, on my 6.5" 500 I had a defective cylinder stop spring.
The tech at S&W told me, before they made the X-frame, they only had one part number for the cylinder stop spring......one number, one part for all revolvers.
They found out that spring wasnt strong enough for the .500 so they came up with a stronger one. He thought very likely they installed the wrong spring at when they initially built the gun....
What was happening was Id shoot 2 rounds and then get an already fired cartridge even though I had all five loaded. The cylinder was rotating back as the recoil caused the cylinder to unlock.
Changed the spring all is well
It happens so I cant say I dont believe it, but as rare as it is I would think the double tap has a good chance of happening in conjunction with an unlocking free rotating cylinder. I think one would know if they went through the complete double action pull even if they didnt intend on it
Improve your grip, but be on the look out for the two shots and click........good sign the spring is the problem