Make certain players see a different image than the others

Just wrapped up a homebrew arc heavily featuring the PCs becoming mad/insane. The more mad they became, the more unsettling things they would see. For a while, a few players would see different things than the rest of the party (a cute teddy bear for the majority was a nightmare creature with glowing eyes and bloody teeth to a few) and how we (DMs) handled that was sending the demonic version to the player privately so they knew what they were seeing without the rest of the party knowing what was up. It would have been far better if we could have tagged specific images with a "dual image" where players in group A would see the "normal" version and players in group B would see the Horrors™. I could also see this working for hiding things and only PCs with a high perception being able to notice something, or PCs with true sight.

Hi Ren S.,  This is already possible in a variety of ways.  If you want to show a Handout to one player you can do that.  If you'd like to show the Bio & Info tab of a Character to one player, you can do that too.  If you'd like to show an entirely different map to one player, you can also do that, although that is a bit more involved. 

Hi Gauss, sorry for the late reply (and unsure if/how to ping you). Thank you for the info. Unfortunately, what I'm talking about seems a little different as I didn't want the players to realize at first that they were seeing something differently on the map than other players. To explain my original scenario more, at one point, our PCs were fighting a ghost girl and her "toys." Now, some of our PCs saw them as their tokens showed: rather cute/harmless looking toys. But a few saw them as horrid nightmare creatures. I would have liked to have been able to tag the token with two images that would display to the player depending on either a tag or manually choosing which player saw which token. Furthering the dual images concept, this could be done for objects, assigning two images to one "object entity" so that, say, low perception players see a rock and high perception PCs see a suspicious door crack. It would give players an advantage due to their perception but still provides challenge to them to actually study the map. Same goes with magical sight or such noticing something off/invisible to other players.

I understand asking for those kinds of features (like what the Twins script does in API mods) to be integrated as Default features of Roll20, and for that I give your Suggestion a +1 . Some (if not all) of what you're asking can be accomplished with Roll20 Mods from the API, with a Roll20 subscription. Some (parts) of that idea can be done in default free Roll20 using the Split The Party onto different pages method.  Another whole route could incorporate Messaging (which could be Discord private messages, or Roll20 PM's if necessary). So each player is sent "You see this" individually at the same time.  But in the meantime, or as a workaround from classic gaming, I think you can achieve that game scene by telling your players verbally who is seeing what, and they'll be willing to intellectually "ignore" the parts their character isn't supposed to be seeing, and save yourself a LOT of setup work in trying to make that digitally visually seperated to the point of perfection. 

Thank you Gold. I'll look into the API stuff with my co-dm who has a Roll20 subscription!