How should I wire for two side-by-side refrigerators?
Ever seen a refrigerator plug?
They have a 90 degree molding on them so they are flush with the wall.  The bend is generally downward (not sideways) to the plug pins.  Plugged into the upper socket, they will block the lower socket.
So 2 fridges on 1 recep is Right Out. You'll need two receptacles.
We had a question a couple months ago from someone who did not realize this until the refrigerators arrived, drywall/paint was done. They had the good sense not to use extension cords, but it was a serious vexation... &quot;extend with Wiremold surface conduit&quot; was our best answer.
Separate circuits if possible
You are contemplating a Multi-Wire Branch Circuit or MWBC.  That requires a 2-pole breaker, or two 1-pole breakers with a handle-tie (which are hard to find, easier and cheaper to use a 2-pole breaker).   So clearly, you have 2 breaker spaces available for this.
The problem is, this creates a situation where one fridge's problem can take out the other fully functioning fridge.  Ask your partner how much food spoilage that would be.  A lot.
We don't like AFCI or GFCI on refrigerators because of the chance of a nuisance trip causing food spoilage.  The problem with MWBC is if one leg trips, most likely, so will the other leg due to the handle-tie.  (2-pole breakers have a feature called &quot;common trip&quot; which guarantees this). And if you put both fridges on the same simple circuit, same problem again.
So my advice is 2 dedicated circuits, 1 per fridge.  The most costly thing is establishing a wire-able route between panel and outlet... once you've done that, 2 cables vs 1 is no trouble at all.  Throw two 12/2's in there, done.  The second most costly thing is spaces in the panel, but you have those.  Throw the two 12/2's on separate breakers, and you're all set.
&quot;Oh I know! I just won't handle-tie a MWBC going into a single junction box. What could possibly go wrong???&quot; The answer is a maintainer getting nailed because they did not realize the neutral was a live wire.  Happens all the time.