I'm glad that you are just using your distraction techniques to seperate the two, but I do feel that you are analysing too much your dogs behaviour.
Quite literally as with children you just tell them to behave, your in charge.

Dogs do and will have little arguments they are usually completely harmless and nothing to worry about, these two have
never drawn blood, just IMO had spats, they argue a lot over all sorts of things just like siblings do and as you know because there is hardly any age difference, so no clear alpha, they will both have their own opinions on differing things which are important to them, there isn't always an alpha especially with just two dogs we don't have a pack here.
You have had so much conflicting advice from different behaviourists over which dog is showing more of an alpha role that it is just best to treat them both the same and just give them a quick telling off, an Oi, Stop, Behave! A clap as you have been doing.
I think what you have to accept is that you don't need to analyse everything that happens, just take it as read that they
will have disagreements, the odd growl, the odd telling off, your not going to stop that completely. I think this is what you need to accept, just react differently to it in not thinking the world is ending everytime it happens. They are
always going to jostle, they are equal characters. But they don't actually hurt each other, so IMO it isn't a problem, it's like two brothers who love each other, get on great but
but heads occassionally. It's to do with character, not necessarily behaviour therapy.
Just keep yourself installed as the authority figure and tell them to behave however you do that, hopefully you will soon not feel as stressed by it, you just need to accept that you are never going to rid them of this behaviour all together, maybe the older they get the less confrontational they will become, but I think you just need to accept that they both have strong characters and can get the strop with each other.