Building on what others have already said, the reason those methods work is because when considering triggers, there’s no real difference between triggers. So if you have two triggers that hit at the same time and you want to choose between the two, there’s no point in choosing, since they’re effectively the same thing. So, with that in mind, what you want to do is effectively just choosing some random triggers from one source, some random triggers from the other source, and then mixing the output together into one trigger stream. As has already been pointed out, you can do this by feeding one trigger source into one channel of Branches, the other source into the other channel, and then mix or combine one output from each channel. A simple mixer is fine, or if you have a passive OR gate combiner that works too, or an active OR like the MAX output on the Kinks. (I wouldn’t recommend using a passive mult to combine trigger outputs. That could potentially damage one or both of the trigger source modules, depending on how their outputs are designed. Remember, in eurorack, it’s always best not to plug an output into an output, to be safe, and that’s what you’d be doing if you connected them with a mult.) Or you could mix/combine the trigger sources before putting it into Branches and save yourself a Branches channel, since it’s the same thing (except you can’t control the probability of each trigger source individually then).
It gets more complicated if your two trigger streams have different voltage levels and you care about getting different voltage levels in your output. Or if they’re gates and you care about getting different gate lengths in your output. (In both of those cases, I wonder if there’s a better way to think about and frame your desired end result that would provide a simpler solution?) But if it’s just triggers, it’s as easy as branches and a mixer/combiner.