I'm guessing the "river going into two seas" is up in the north , with a dot right in the middle. That's actually two rivers, one coming from the west and another from the east. The two rivers come within maybe 10 miles of each other before diverging off in different directions.
This is absolutely credible in real world terms. In northeastern Bavaria in the Fichtelgebirge range (Spruce Mountains) the watersheds of the Rhine, Danube and Elbe meet and sprout four rivers. Within 10 miles of one another are the sources of the Main River (Rhine tributary), the Fichtelnaab (Danube tributary) and the Eger and Saale Rivers (both Elbe tributaries). Three separate watersheds coming together, as in this case, is a bit unusual, but two watersheds meeting is normal, in fact, it cannot be otherwise. Anywhere where the ridge line that defines watershed boundaries arise, springs can and do come up on both sides of the ridge that flow into different watersheds. Don't let anyone tell you that there is anything unrealistic about this idea. It is, in fact, the way it works in the real world. However, it would be very strange if you had two rivers flowing different directions out of the same swamp (lowlands), because a swamp hardly would define a watershed boundary.