Well there are two or three schools of thought.. First most RV's have way too much glass to insulated (not all that well) wall so when it gets sunny, it gets HOT.. of course opening said window can fix that. In most cases.
Now, double pane, does insulate better than mono-pane and it is true the seal between the two can become compromised, and some are filled with odd gasses that react with the glass and bad things happen (not all) and when bad things happen instead of being double Pane they become a double Pain in the wallet.
BUT. that said.. One of mine failed.. Some debris damaged the seal between the panes.. I damaged it some more. blew some 'Damp rid" up between the glass. it settled down in a corner where I have to look to see it (Completly out of my normal vision) and sucked up all the mositure, as it is intended it will, I fixed the seal, and all is good.
Odds of that being a successful repair... Dang Low. But it worked.