What do you mean by drift in the framerate? My understanding is that there is not so much a drift in the framerate, but there is a drift when the camera beginns to readout the first line from the CMOS. I think that will differ.
OK, then the language barrier is why we may not have understood what your complaint is. I thought you meant the frame rate was drifting about 23.976 fps, like plus or minus 2 fps. Sorry I misunderstood your use of "drift".
Here it is quite likely that the start moment of the first trace in the first frame will start at different moments within the first recorded frame. However, I'm afraid you are now asking for something that will never happen with our consumer camcorders as consumer camcorders lack the circuits to achieve this match. The technology does exist, however. It's called "Genlock" I have mentioned this over and over before but maybe I was speaking to an audience that does not know what Genlock is or how it is used in multi camera production, and most important, what is required to use it. Let me explain for anyone who is not familiar with the concept of genlock.
Genlock is a process where a camera in a 2 or more multicamera shoot is designated the master clock. This camera has a sync output jack. It also has a time code output jack. (In TV studios, the master clock is usually a device and not a camera and all cameras will be locked to the device.) In broadcast cameras, there are four such jacks for TC and sync input and Time code ad sync output. Consumer cameras have none of these! The master camera is set for "free run" time code drop frame for those in the NTSC world. Drop frame is required so that the clocks in the camera will frame count to match the real world clocks.Special note about consumer camcorders- A consumer camcorder with a composite video output jack could be used as a master clock because the video composite signal would contain the necessary sync required for the slaves. But this would present one limitation and that is no time code. This would not be as important in a 3D setup because one could still use the markers, clap board slate for clip match.
Now we set up our first slave camera by putting the time code into free run mode, drop frame, lock to external input. Some cameras this setting also puts the slave camera's clock to reset and lock to an external sync. Others may need a menu setting to switch from internal to external sync. A short cable is now connected between the master and the slave. In a few seconds the slave will lock onto the master and now both cameras are in lock precisely to one oscillator clock phase. The start of a frame or field will be at exactly the same moment down to the microsecond or better. Now we can discon the cable and "genlock" the third camera in our shoot. (Not necessary for a camera pair) Some newbies believe that if you disconnect the cable you will lose genlock but this is not true. Cameras will remain in genlock ( subject to some drift over many , many hours, days even) unless the slave camera's internal memory battery is dead. ( repair issue). The beauty of this system is now you can start and stop any one camera in the genlocked production on it's own and later match up the recorded clips to the exact frame by time code in post. Two cameras that have clips recorded that overlap in time code will obviously also have the same action recorded by two different cameras at EXACTLY the same moment in time, including the start of of each frame or field 1 of the first match frame.
So, what we have are cameras that are genlock capable to achieve what you are bemoaning about. The technology does exist and has worked for many years. I have done well over a thousand TV shows using this process and it became quite routine.
There is another technology that could align your frames to the exact moment you are requesting you need for your work. This is a frame store synchronizer. A bit of history- In the early days TV stations were mostly internal and never needed to mix their video with external sources for live recording and broadcast. But then along came microwave network links and later still satellite links. The problem was that the signals could not be genlocked over such a long distance because TV signals travel at the speed of light and there is a significant delay that far exceeds the nanosecond delay in a cable between two cameras. So the frame store synchronizer was added and what this does is delay one video signal to match up to another in real time so the frame start is in lock. These devices sound expensive and complex but in reality they are readily available. The first really popular frame store device was the Video Toaster. It could take 4 asynchronous video signals, even VCR's and synchronize them to match frame. I'm not sure how this would work for a 3D camera setup to mix the signals but the frame store would match the frame start for you.
So, I have given you two ways you can do what you claim you require to shoot 3D in match frame. Genlock cameras ( the simple but broadcast cost way) and a frame store synchronizer, but this may require some additional hardware to generate the 3D frame packed or SBS for display. Some frame store devices would output the independent videos too after they were frame matched. I don't recall if the Toaster did this but, you will need one that does HD resolution anyway.