Multiple Written exams

Hello,
I am going for CCIE security written exam in coming month of Jan. This will
refresh my CCIE for next two years. But i am a bit confused if i will go for
security or service provider track. So i am also planning to give CCIE
written for service provider in couple of months. Will giving two written
exams refresh my CCIE for 4 years? or it will be limited to two years only?

-- 
Khurram Noor
CCIE # 24419
http://www.linkedin.com/in/khurramnoor
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