Slots 29 and 30 are reserved for the autosave feature. The game makes a save into the 30th slot each time you change a zone/map. 29th is used each time you talk with Freak so you could load to the point before you went on the story mission. All other slots are open for use. I don't know how you've got 27th, 28th or any other saves via Itch.
I even looked up archived versions of v0.1. There are two of them since I made a hotfix. This is the first one and this is the second one. dated 15.12 and 19.12 respectfully. Both don't have any save files in the game folder so it's beyond my understanding how you got these weird saves through Itch's installer.
Anyway, if your save files were overwritten the only way you can get them back is through file restoring utilities and software like Acronis yet I'm not sure if it will be easier to just start over.