This is one reason why it's often thought that a long-term station in Earth orbit (possibly at one of the Lagrange points) is a pre-requisite for a Mars mission. So, you could decelerate to the station instead of to re-entry. But, it is possible if one sent enough supplies ahead.
One way of handling things if there's a long-term station is to build the ship to Mars in space (or at least refuel at the station). If you send the return fuel ahead (or find a way to make it while at Mars) you aren't required to carry a large amount of fuel.
You still have to carry twice the fuel. What about a refuel station orbiting mars? Replenish the mars fuel station with fuel before the manned mission departs, they can just use that fuel stored at Mars when they return from the manned mission.
One way of handling things if there's a long-term station is to build the ship to Mars in space (or at least refuel at the station). If you send the return fuel ahead (or find a way to make it while at Mars) you aren't required to carry a large amount of fuel.