Oddundation

I recently came back to this game after about a year and I noticed the spell Inundation behaving oddly, I couldn't find any notes on official changes so I thought I'd ask here.

Specifically, Inundation seems to be able to overwrite itself, you can cast it repeatedly on the same mob and the log will give you the '<t> is Inundated.' message each time. No other enfeebles will do this, as they will give you a 'no effect.' message when the mob is already afflicted by the same enfeeble (and recasting Dia/Bio will not extend their duration) and I do not remember this happening with Inundation before I left.

Is this a bug or is it a change to the spell that I just wasn't able to find?