As though your hearsay could possibly qualify you to make that judgement!
The church rejects the idea that a marriage between baptized persons can be "dissolved," so you aren't going to hear of those at all.
The only question is whether a marriage ever existed at all.
There are plenty of cases where someone attempted remarriage after a civil divorce. If their first marriage was valid, their second marriage cannot possibly be valid if their (original) spouse is still alive.
Declaring the second (attempted) marriage invalid is perfectly Biblical; in fact, Christ's explicit words, related in three different gospels, require it.