Premier Elements -- matching different years, for lossless merging

I've been using 2021 Premier Elements for years, now trying Elements 2025, want to get newly saved mp4(2025) files to match parameters of older mp4(2021) files, close enough for high-speed lossless merging in Bandicut. I've matched frame size, frame rate, constant bitrate numbers, keyframe rate, and audio traits, but that is not good enough for Bandicut, which is saying, “no, if you want to merge those two mp4 files together, you will have to use slow frame-by-frame encoding.” How many more parameters do I need to align, and what are they? I’m using a Windows 10 system, to create 1080p files, CBR with target bitrate of 11 Mbps.