Extracting image stream from dual ISO .mov created with Magic Lantern?

Hi,

Magic Lantern was a Canon DSLR hack that offered dual ISO recording. This created a high frame rate .mov in which alternate frames were +2 and -2 stops around the set ISO. These two streams could later be blended to yield a faux HDR result.
I shot a short film with this 12 years ago, and post got temporarily shelved.  I'm back on the case now.

So far:

Import original up/down 50fps footage. Put into two separate 50fps compositions. Give one a one-frame offset. Change compositions to 25fps. Both comps look great - one up and one down.

Now, I can blend these two using AE's HDR Compander, but there's a temporal offset of 1/100th between the two exposures, so anything moving has a ghost. The only fix I can think of is rendering one of the 25fps compositions as a series of tiffs, and then to reimport it. I would then halve the speed of the footage using Time Stretch and AE would generate the missing frames. From there I'd extract those in-between frames as a fresh 25fps comp that would be in sync with the other comp, and I can then blend the two.

All kind-of straightforward, and I can create a template to repeat the process for each shot. Straightforward EXCEPT the cumbersome step of exporting tiffs to later have to reimport them. Can anyone here think of a way to avoid this?

What trick am I missing?

For the curious, here's a video showing the Magic Lantern HDR hack

Cheers!