Infant baptism strikes me as worse.
So would you encourage anyone who remains Christian who was baptized as a baby to be rebaptized? I guess you'd approve of me "invalidating" my infant baptism by getting rebaptized in a few weeks.
"Invalidating" Baptism? Dude, it's a
Sacrament. Either that charade your parents went through when they had you baptized as an infant was not a Sacrament at all but a mockery of one (and thus probably blasphemous to boot; not consciously of course, not saying that at all), and then there is no reason to bother with invalidating though you do need to be rebaptized; or it's valid anyways and you can't invalidate it (though I guess you could still be rebaptized just for, you know, yourself and the world, rather than God).
While I've heard of errors of ritual "invalidating" a Sacrament, I've never heard of some kind of "invalidating ceremony". That seems to be an innovation to Christianity quite as strange and disturbing as anything the Mormons come up with.