If you want to leave the old box, just buy a double size cover with only 1 opening. (Or a blank insert for the 1.) https://www.amazon.com/Leviton-80608-W-Combination-Wallplate-Thermoset/dp/B000U39WQA
If you want to actually just have a single size cover, gotta swap the box AFAIK.
> I was curious if I could merge both switches into a single Lutron Dimmer to control all 10 lights ?
Yes, just check that it's an LED capable dimmer and that it can handle the total wattage through all 10 lights. You're probably in the 9 - 15 watts per light range depending on how strong your bulbs are. Don't push it right up to the dimmer limit. Might also want to double check that you have a common in the box; most of those Lutron dimmers require it.
> Also are there any double covers that have a single switch hole in the middle ?
Yes, but you'll most likely want one with the big rectangle (rocker) instead of a small hole for a traditional switch. Most dimmers are rockers though you can find them in traditional switches. You might also be able to find one that is centered, or you could rip the entire box out, put a new one in setback a half inch and put a mud ring on.
You're gonna have to open that wall back up.
You can replace the single-gang junction box with a double-gang, put your switch in it and cover it with a Decora half-blank plate. That keeps everything on one side of the stud and will give you a little extra room for wires in the box, depending on how deep that switch is. You might be able to replace that junction box with an extra deep single-gang box (if you can find one) to give you extra room as well.
I’m assuming this is why Amazon sells these, to save me $191 lol…
First things first, we need to know the actual product you're using. There is no "Ring Pro 2." There is either the Ring Video Doorbell 2 or the Ring Video Doorbell Pro.
They have vastly different power requirements, and one will be doable without much modification and a basic transformer and chime swap (the 2), and the other will be complicated and require modifications, possibly an electrician, and a way to cover them (the Pro).
If it's the 2, you can install a Nutone C915 16VAC@10VA transformer in the box where the AC power comes in (the Nicor box is split into two halves, high and low voltage). Be sure the breaker that powers the doorbell is off first. Then the wires just get swapped like for like to the wires on the back of the new transformer: black to black, white to white, green to green/bare. That would connect to the back of the transformer and it would screw into the high voltage side of the Nicor box.
Then, with the wires leading to the button, you would connect one of them (doesn't matter which) to one of the transformer yellow wires (again it doesn't matter which) with a wire nut and tuck it into the low voltage side of the Nicor box. Then you'll have one button wire and one transformer wire left, and those get connected to a basic mechanical chime. Connect the yellow transformer wire to the trans terminal on the chime, and the other button wire to the front terminal on the chime. Then you mount the chime over the whole Nicor box and new transformer, covering it up, being careful to ensure the yellow wires don't get pinched where they run from the front of the transformer over to the other side of the Nicor box. All the mechanical chimes (per brand) are the same inside, and generally all that's different is the cover. You may need a slightly more expensive chime with a larger cover to completely cover up the transformer and dual box of the Nicor. I recommend going with a Nutone (or Braun, it's the same company) for the chime too. Avoid Hampton Bay and Heath/Zenith, as they're low quality and fail frequently and tend to hum while the battery in the doorbell is charging.
If it's a Doorbell Pro, well, it's not going to be easy. It can't go there and meet code still. The 16VAC@30VA transformer that the Pro requires is way too big for the Nicor box and can't just be mounted in the wall. It would need to be wired somewhere else that meets code and new wires run from it to the existing Nicor location. Not fun or easy or cheap. There are two other options for powering the Pro, though with either you would have no mechanical chime, so you'd have to use a Ring Chime (or Echo devices or the Ring app alerts) to have any sort of notifications at all.
Option 1: Ring sells on their website, not on Amazon, a plug-in transformer for the Pro. It cannot be lengthened or connected to other wiring, you plug it in and run the wire to the Pro, but this will require drilling somewhere to get the wire to the Pro.
Option 2: Replace the Nicor high voltage side with an electrical outlet and buy a cover plate with one blank side (like this) and [one of these plug-in https://smile.amazon.com/MG-ELECTRONICS-MGT1640-TRANSFORMER-40AH/dp/B001DPNQ0M/). You'll also need about 12" of 18ga SOLID NOT STRANDED bell wire. It can be more than 2-stranded if you use thermostat wire, for example, which generally has a sheath on the cable but comes with 2-6 wires depending. Sheathed cable will look better, and if you can find white, even better. Your local home center should have it. You can use just bell wire too, which is generally just two wires twisted together and are different colors, but the sheathed cable will look better. Your local home center will have a variety but make sure it's solid core and 18ga.
You mount the outlet into the high voltage side of the Nicor box. Drill a hole in the blank side of the cover place where it looks nice and is big enough to pass through the wire you're using. Strip both ends of the bell wire to about a half inch. Do the same with the button wires. Attach one of the leads of the wire you're using to one of the button wires with a wire nut. Next take the Pro Power Kit v2 and peel off the tape to expose the bypass mode holes on the long edge opposite the two black wires. (You won't use those black wires. Just leave them there.) Take the other button wire and push it into one of the bypass holes on the power kit and make sure it goes in all the way and tug on it to make sure it's seated and the clamp is biting into the wire. Do the same with the other conductor of the bell wire—insert it into the other bypass hole. Now pass the bell wire through the hole you drilled in the wall plate, and drop the Pro power kit and wiring into the low voltage side of the Nicor box, and affix the cover plate over the outlet and empty space. Connect the bell wire to each of the two outer terminals on the transformer (again doesn't matter which is which, just use the outer terminals if you happen to get a 3-screw model) and tighten the screws. You'll need to remove the screw meant to hold it in place, since your outlet won't have that hole. The orange washer just pulls off and the screw comes right out. Then plug it in, turn on the breaker, wait for the Pro to charge up and indicate it's ready for setup and begin setting it up. Once you know it works, I'd recommend a strip of 3M command adhesive behind the transformer just so it can't fall out since it's heavy and you can't use the mounting screw on that style outlet.
OK, that about covers it, if any of that makes sense to you.
The only other thing I can think of is this, it removes the need for the insert, but you are still stuck with your switch being off centre.
http://www.amazon.ca/Leviton-80608-W-Combination-Wallplate-Thermoset/dp/B000U39WQA