I have some subtitles where in the video there are English and two other languages spoken, but only one is translated in the main subtitle SRT. There's a second subtitle SRT file that has both non-English languages translated but none of the English is subbed.

Looks like the common language between the two SRT files is timed the same in both, so I need a tool that can find and merge only the entries that aren't in the main SRT.