Photon Colour

This is not so much a tech tip as a tech question. I've found that with one point light and one area light in my scene if I set them both to emit photons I can't get them to emit photons of different colours.

They either default back to white, or back to the colour that I set for the first light.

In the attribute editor I'm able to edit the colour and it looks as though it's changed - but the next time I go into the AO for the relevant light the colour has defaulted back to one of the scenarios described above.

Either I'm missing something really obvious or it's a bug in maya so if anyone has any answers please let me know.