Yes. I have not watched the video but saw no reason not to remount both the front and rear backings for support.
I didn't even try to see if it would fit nor did I question the technique in the video. Too bad I threw away my extra pieces. Hope it doesn't matter in the end, but I do see the potential strength gains of mounting both.
The more I think about it, the dumber it seems to be drilling anything out and not to just simply put the whole liner right on top of the existing half ones. Does it make any sense that we had to manually separate the parts before putting in the complete liner? I wish now I had tried to just put the liner on top of the halves after taking out only the screws without making any additional modifications. Maybe has no different effect but it would be more logical at least. It's probably why there aren't any instructions. It's so obvious to them that you remove the screws, put the liner in and put the screws back in.
I wonder if anyone with the liners from the factor can attest to whether those halves are still there, front and back, and whether the rear one has only the backing left (like the video).
If this video is wrong (and this thread is wrong) or less than ideal, someone should say something so people don't make wasted/worse changes while trying to upgrade.