Rivers can bifurcate locally, yes, but if you’re finding yourself joining two major rivers with a cross-tributary, you really have to ask yourself: “How many directions can a river flow in at once?“. Hint: the answer is not “More than one, I think?“. In the real world, the different parts would have different flow rates, so one of the two would quickly shrink and eventually close off as it silted up.
Of course, we’re all adults here, so don’t even need to mention the fact that rivers can’t connect separate bodies of water.
And don’t get me started about catchment areas.