Wiper arm sizes different?

Hi, I recently realised my 2007 Jimny JLX has wiper arms off different lengths.  Is this correct and, if not, what lengths should they be please?
At present, the passenger/left arm is about 2" (50mm) longer than the driver's/right.  Both have 16" blades.
Cheers, Chris

Yes my passenger side is around 500 mm 
Driver 450 mm
I also use 2 16" blades
I think standard is 18" blade on driver side 

Thanks for the confirmation. I had also seen somewhere that the driver's side could use an 18" wiper.
Chris