Im interested in buying a 4plex but should i buy 2 duplexes instead?

Its always a bit less trouble to have more units in one place but if the duplexes are a bit cheaper they may still be the way to go. Likewise if you could buy 4 individual units for way less that may be the way to go. Still, it is nice to have more units in one building - just easier in lots of little ways.