If I make a normal mosfet and import the spice with Magic, it creates a mosfet with a gate contact on each side of the gate. I can edit the pcell and turn off one side. If I do the same with a multi finger mosfet, I can't turn off the double sided gate contact. Does anyone know why?

There are some restrictions on multi-finger FETs which are very short (small L) in which the poly contacts cannot be put on the same side without causing DRC errors, so the only way to fit them is to stagger them top and bottom. I've been wanting to add an option to the device generator to allow all of the gates to be connected together which would avoid the need to do the staggered arrangement. It could also be done by allowing the diffusion length from the gate to source/drain contact to be longer. Otherwise, once the gate length is around 0.28um, the staggering is no longer needed and you can select top or bottom. I just discovered that the staggered arrangement prevents turning off both top and bottom contacts, which would allow you to draw your own (if there's room, which there might not be), which is an unintended error.

Thanks Tim

@Matt Venn: Is there any part of this that you need urgently enough that I should go upgrade the device generator script in the PDK?

no