The reason you sometimes see higher than 1 parallel is just packaging. If you don't have cells just the right size to fill a battery compartment, but have cells that are right at half the desired size, bingo just double them up in parallel.
No worry about balancing, the cells in parallel will continuously balance with each other. All the time whether being used or not (within a single assembled pack anyway). Normal balancing still recommended for the series portion.
The only concern is when assembling the pack, should have all the cells at the same voltage. Any difference, and the balancing will happen very quickly, could cause some high currents.
Last edited by Dave H; 10-01-2009 at 02:17 AM.