You will need to combine the two white wires into one and put it in the single C spot.

The fuse will keep blowing usually if you have a bad solenoid. Usually when it gets to that station.
You can use a volt/multimeter to test for bad solenoids.

Checking solenoids and field wires
1) Set meter to OHMs
2) Set range to 200
3) Remove common wire
4) Hold tip of black probe to common wire
5) Touch red probe to each station screw
**Short circuit/Bad solenoid/Wire=0-12 ohms
**12-60 ohms Good solenoid
**High numbers=corroded wire
**200+ common broken

http://help.rainbird.com/app/answers/detail/a_id/79/~/i-have-a-blown-fuse.-what-do-i-do%3F

Thank you - I have combined the whites and I seem to have fixed the fuse problem by going up to the next MA. I now have a fully functioning sprinkler system again, just in time for the hot dry weather we are having.
Many thanks for your help.