parallel panels via their junction boxes

Its an NEC issue.
That is whats known as "double lugging."
A lot depends on the UL rating of the terminals in the PV modules J-box. Even if each screw/clamp terminal is UL listed as being able to have double wires and its UL listed amperage ratings are sufficient, a lot of inspectors still don't like to see it. What does the manufactures spec. sheet or warranty have to say about it? Anything? Diodes?
Think about how, not just the amperage from the one PV module is passing through the screw/clamp terminal but the amperage of two PV modules. Or more if several are "daisy chained" in parallel. There is also the issue of the UL listed amperage rating of the combiner box, the total amperage, not just the individual PV module circuits. 6 - KC40T's in parallel after the 156% would be close to 25 amps.
(On a side note, something that has always irked me about residential, 15 amp, 120 vac duplex wall receptacles, on a 20 amp circuit, is that little flimsy piece of metal jumper between the screw terminals. In Commercial use, the current carrying conductors must be bonded together with a single "pig tail" that hooks under the screw.)
Of course its not just at the PV modules in your case put at the combiner box which most inspectors will treat just like a power distribution or "breaker" panel. There again some, like the Square-D, QO breakers are made with the screw/clamp terminal that can hold two wires. But a lot of inspectors still don't like to see it and they don't like to see power distribution panels used as j-boxes so a "pig tail" may have to be done in a separate j-box first.
http://photovoltaics.sandia.gov/docs/John_Wiles_Code_Corner.htm
This one in particular.
http://photovoltaics.sandia.gov/docs/PDF/Code_Corner_96.pdf
I hope something here helps you.

O.K. I got it....need to upgrade my combiner box to add in more panels...

Thanks Thomas & James for the info!