As others have already said, players can edit the initiative value (in this case, the "card") for tokens they control in the initiative tracker. This is not a bug. Roll20 by design supports a lot of other games besides just Savage Worlds, where this type of behavior is desired, not discouraged. In general, Roll20 does not enforce games-specific rules. For example, you can only move tokens you control, but you can move them however far you want, even if your game rules say "only 10 feet." You can only draw cards from decks available to you, but you can draw as many as you want, even if your game rules say "only draw 1 card this turn." You can only modify the HP of a token you control, but you can set that HP to 9,999 even if it should be "30". The list here is endless. Roll20 is designed to emulate a tabletop, and just like a tabletop, there isn't a magical rules enforcement robot making sure no one is cheating. Tabletop games are the worst games to play with people you think would cheat -- it just ruins it for everyone. EDIT: If you don't want this functionality, instead of adding tokens themselves to the turn order, click on the gear icon, and use the "Add Custom" feature to add your names to the list. Then only the GM can edit the initiative value of each.
