The most common diplopia is created when we look way up or way sideways. This can be solved by, 1.) Having single vision shooting glasses, and have the Optical Center set up higher; your doctor had you get in a shooting position, this is the same position that your OC should be measured in for those shooting glasses. and 2.) Occluding the left eye ( in your case) as you have been doing, by tape/frosted lens, or shutting your eye. I've found I shoot better when I shut the left (my dominant eye) completely when checking the beads for correct mount, then open it about halfway after my line of sight has shifted to my soft focus area, which is
above the beads, and proportionately to the side of it, depending on the post I'm on. As Nitro Pilot says, you are still consciously registering the beads and barrel when going to you soft focus. Try a really low hold, (front of the traphouse) then moving the soft focus up to the point where you stop doing so. (where you'll see the birds come out) You've already checked your mount, and as long as the wood stays on the wood, your subconscious will take care of the rest.
The eye will focus 'back' from farther away to a closer object faster, particularly if it is moving, than from near to far. This is why soldiers in combat develop the '1000 yard stare'.
The hardest part is giving control over to the subconscious once you've done everything else in your pre-shot routine.
Likes-to-shoot,
I don’t know about the eye dominance; it doesn’t seem to be an issue using both eyes open.
There is a concurrent thread on here about that; for most, the BB gun training does work. Not only do we use this 'method' of looking hard at one thing and noting another in the periphery driving, but most probably do it hunting too, and don't realize it.