while possible, it is annoying. once you placed a splitter, you cannot connect belts to it if it has another splitter in the belt below due to object encroachment.
you have to remove the splitter below, probably belts connecting to it as well, place the top splitter, connect belts, then bottom splitter and connect belts.
and dont get me started on mergers as well....
this could all be resolved with a simple stackable splitter/merger.