Delta V's are independent of mass or number of launches. It is simply the change in velocity needed for any object to move from one orbit to another. You do need at least 2 launches and Mars Direct actually calls for 3 with a backup ERV going along with the crew. If not needed it is the primary ERV for the next mission so that over N missions you have 2N+1 launches. As N becomes large this gives an average close to 2 launches per mission.

I'm not sure what you meant by Moon scenario. If you meant Apollo's mission profile, it needed one launch but resulted in a very small payload compared to Mars Direct. The Moon Scenario with refueling on the Moon could require one launch but ignores the many launches needed to build the fueling capacity and the fact that you could have gone straight to Mars on less fuel. It would be far easier to build a permanent refueling station on Mars than on the Moon because water is far more abundant and using the atmosphere's CO2 would give you far more fuel per pound of water. Since CO2 is far easier to collect the effort/cost per pound of fuel would be much less on Mars. Build the more cost effective refueling station on Mars and it only takes one launch per mission as well.

Regards,
Mark