Command "/testfor" outputs a true signal even after re-running command when a player is teleported

This bug only works on multiplayer (as far as I can tell)!

At the spawn point: create a clock connected to a command block (CB) and set this command to "/testfor @p[r=3]" set a comparator to feed into another CB with the command "/tp @p[r=3] x y z" {teleporting out of range of the the command blocks radius}.

The testfor command detects the player who triggered it and activates the comparator which stays on, and the teleport will trigger. Because the spawn chunk is always loaded the clock will keep cycling and running the testfor command, >>which should deactivate the comparator<<. Instead, the comparator stays active and the teleport command is run again.

Note: The screenshot attached describes the set-up I used, however this is not the only set up which will result in the aforementioned error.