maybe i'm playing this wrong but if i'm pretty sure i'm in a split pot i'll sometimes go all in to try to scare them off the pot, if its a three way usually one of them has the weaker hand so its still worth betting imo.

In SS Doyle reveals a great trick for split pots in live games. It goes :

You and another person are in a split pot with the nut straight on 4th street. You know as he has just reraised you and tried to take the lead. What you do is study the flop as if you didnt realise the straight was close and then after some time say "damn it i call" if the 5th card pairs the board you move all in straight away. The other straight if any good will think you have hit your FH and fold the split pot

This can work online if the players are good enough to see what hand you are representing a lot just play there own cards though.