@Solistia
Well, if you update them simultaneously, and their release rate and narrative progression aren't too different, it'll make for some fun direct comparisons.
Still seems kind of a weird occurance but, I guess if you can get away with doubling your exposure (and profit, assuming those aren't free web magazines), then how many authors wouldn't go for it? Hopefully the author being able to pull that off is an indication that the light novel is good enough to warrant the extra attention (and thereby, that the manga'll likely be good). ^.^