Buy the strange pill from the shop and use it during battle, then get whichever scene you want to unlock the second round for.
Note for cowgirl: You need to use the pill on your 3rd death. Using the pill on your 1st or 2nd death renders it useless.
Long note for sideview blowjob: It's currently impossible to unlock its 2nd round normally, however you can edit your save to unlock it.
If you're on Windows, press Windows + R and type in %appdata%, then go through Godot > app_userdata > Love Maniac > save, then open meta.json.
Change the "side_bj" line from false to true under "unlocked_scenes" and save the file.