Help is simple: do NOT give them toys when they are together, or chews, or feed them near each other. This is a common problem with having more than one dog.
They are starting to fight to establish or to assert rank, and is typical especially if you have two of one sex. This most likely will never, ever stop -- and you simply cannot set up trigger situations by giving them toys when they are around each other any longer -- they can and WILL fight viciously if given the chance. Leo and Jaspar will really go for one another in certain situations and so I avoid putting them in confrontational situations (this BTW is one reason most trainers advise getting a second dog of the opposite sex -- this is far less likely to happen. Cavaliers are generally better than a lot of breeds but the conflicts will almost always arise between two dogs, both the same sex, in a two dog household).
The solution is that they only get fed, get chews, and get toys when they are in crates or otherwise physically separated (eg get a puppy pen -- this is one of the best investments I have made for managing more than one dog).
Do not ever allow one dog to guard a toy or chew or ANY item and let another wait to try and grab it -- that is one hour of building tension that is only going to end one way. The nanosecond one of my dogs starts to growl and protect a chew or toy, that's it -- I use a phrase to mark that their behaviour has ended their fun ("You lose!' or 'Sorry!' are two suggestions) and I take the item away and that is that.
If a fight breaks out, "You lose" and they both go into separate rooms for timeouts for 10 minutes then are allowed back out -- and the item is removed, never to be given again to either dog when the other is also around.
But as I said the correct approach is not to allow such a situation to occur ever in the first place. You now know you have a trigger situation if they have toys, chews etc when both free to roam and interact and look at each other. So toy time now has to be on their own, chew time on their own, etc, out of sight of each other. If they are allowed to continue as they have been this is definitely going to escalate into a serious problem and they may become dangerous not just to each other but to humans trying to intervene -- and can progress to general food and toy aggression with people s well as dogs. Keep them PHYSICALLY separate but equal for toys/chews/any value item. Anyone who has dogs that will regularly fight cannot rely on supervision alone -- the dogs need to be physically separated. This is what crates are great for.