MeGUI and Automated 3pass - File exists?

[Asterra]

I've tried a few encodes with MeGUI, and each time it gets to the third pass, it complains that the file exists and asks if I want to overwrite it. I'm forced to say no, so it skips the third pass and muxes as a two-pass encode. I've tried editing the third pass to change the destination filename to something besides the same exact name as the second pass, but MeGUI won't let me.

I don't really care if the quality gained from a third pass is "minimal". I have the time to spare. Just need it to work. ;p

[poisondeathray]

It's not minimal gain. It's no gain.

You can test it out for yourself (I have)

There is a very very very minimal gain, in some source types, under extremely rare circumstances, on a full moon, if you do the 1st pass with slow settings using CRF for the 1st pass (instead of --slow-firstpass)

You can search Doom9 - there are tests confiming this, and the dev's have also commented