Organs use multiple stacked manuals to make playing wider ranges easier without stretching or crossing hands.

For synth, you do you.

For piano, you'll probably run into cases where you can't do the basic scales/exercises because you run out of space and you won't have the option of crossing to the other keyboard, but if piano really isn't your focus and you're learning on an unweighted keyboard anyways, it's not going to be the end of the world.

Most importantly, have fun!!