I would be taking the RER C train from Javel to going to Versailles, but coming back I need to get at Champ De Mars instead of Javel. Is that possible on the same ticket?
You can't use the same Paris RER train ticket in both directions, unless you never leave the interior of the RER stations. The RER Ticket is good for entry past turnstiles / gates into a station, but won't be good for re-entry from outside of a station, back inside a station, once you've left.
If you're asking can you use the same priced Paris train ticket (i.e. you would have 2 tickets), then it depends on whether your return destination is further or closer from the return leg station of origin. If the return leg is shorter / closer than the outgoing leg, then yes you can use the same priced ticket.