Spattering Disjunction can't overwrite itself, as its cooldown is too long even with perfect reduction. But it can and will replace the same status effects if they're already on the target, and reapplying those status effects through other means likewise overwrites them (except Hemorrhaging, which stacks by nature).

That said, it can't cut off actual damage ticks from most status effects, as most of them only do up-front damage (Chilled, Concussed, Diseased, Overcharged, and Sundered). It's only Burning, Hemorrhaging, and Poisoned that have DoT ticks, and Hemorrhaging can stack, so you may not be cutting that off at all.

There's no cooldown on status effect applications, so if you apply Overcharged with Spattering Disjunction and with your Arcanist abilities in the same moment, you'd get two separate instances of the instant damage. You just wouldn't see a real benefit with the passive effects, like Minor Lifesteal.

Spattering Disjunction's utility comes from being able to give additional procs of these instant damage status effects you're already applying, as well as status effects you may not have access to or have poor access to.