Guild Wars 2

If I put a Superior Sigil of Earth (60% chance to bleed on crit) on both pistols, is that a 120% chance (assuming effectively 100%) at a single stack of bleed, or is it two individual 60% chances at separate stacks of bleed? In other words, can a single crit apply two stacks of bleed if both sigils proc?

I guess sigil in off-hand weapon works only for off-hand skills. Just a guess though.

Your second guess is almost right. Those are two individual 60% chances, but they can never both proc on a single crit because there is a hidden cooldown, and it is shared between both sigils.
If your first sigil triggers the bleed than the cooldown starts and none of the sigils can apply another bleed for the next few seconds (5 seconds if I remember correctly), but if the first sigil fails than you can still apply the bleed from the second one. This gives you 84% chance for a bleed total (60% + 40% * 60%).

And both sigils work on all your weapon skills, mainhand and offhand.

So it is better to have something different in off hand?

Generally yes.

I would recommend an ability that gives you a stat on kill as that benefits kits as well (though you cannot get stacks with kit equipped)

ah so like the one that stacks condition damage? forgot the name

thanks