In multiplayer, transporters will often not detect a player walking onto them. Additionally, the transporter stays active for a very long time after being activated, unlike in singleplayer, but it still seems to have the same functional duration: The computer and visual effect just continue to indicate that the transporter is active, but it does not seem to be functional during this period. (However, the difficulties with getting a transporter to transport you in multiplayer in the first place makes this hard to test.)