2 x CAN-bus shield on Arduino mega

Hello,
is it possible to use two CAN-bus shields on an arduino mega?
I want to use one port for reading informations from a vehicle CAN-bus and the other one to communicate with another device, but not on the same bus to avoid problems with the vehicle.
I can't find information about this anywhere.
Thanks in advance.

is it possible to use two CAN-bus shields on an arduino mega?

Look at which pins the shields use. Or post a link to the shield in question, so we can.

Thank's for your reply.
For example this shield: http://www.seeedstudio.com/wiki/CAN-BUS_Shield
It is wired at the SPI interface.

david44:
Thank's for your reply.
For example this shield: http://www.seeedstudio.com/wiki/CAN-BUS_Shield
It is wired at the SPI interface.

The SPI interface will allow any number of devices to share the bus. Section 5.1 shows how to change the slave select pin. Do that on one shield. Leave the other one alone. Then, you can chose which one to talk to, by setting the appropriate SS pin HIGH (or LOW).

Well, for newbie) what's the minimal device set to build a "bridge" between two CAN nets, being able to read, write, and modify headers of messages? I mean, what model of Arduino supports two shields, etc. Or how to build anything similar to CANBUS Triple project? Thankyou