Character controllers hitting each other desyncs, any fix?

Hi, I am building a multiplayer server-client architecture game and I have come up with a system where the client can update his character controller moveVector around 15 times/s. The calculated moveVector is sent to the server 15 times/s and the server side character controller also does these movements.

It works quite fine for what i need and sync's pretty well, however I am having an issue when 2 clients collide into each other, the client side outcomes are different then the server side outcome. I am using uLink so server side physics can be calculated.

Can you suggest anything that can help me decrease/remove this syncing problem on 2 character controllers colliding?

Thanks in advance,
Darren.