Actually it's because your main is not really where you see it is, it's actually the place you where *** ms ago (this is the mains latency) the alts follow that position like glue. But they are not where they think they are either and also *** ms behind (their latency)

So the space between your characters is really your latency + the alt latency.

You can also see this if you jump, hit space and you jump imidiatly then all your alts jump very shortly after. To a spectator, this will actually look like all characters jumps at the same time (almost it's not always the ping is the same across the alts even if they are on the same computer). Since the command was give to all the characters at the same time, so it travels to the server which acknowledge it, since the ping is roughly the same across alts, it will see it as them all jumping, at the same time, and relay it to everyone else watching.