So i went to fight the formless flesh level 5. The fight went on as normal, but quickly two adventurers fell, one to poison and one to bleed. I abandoned the battle and fled to the hamlet. However when i got there my roster said 29/30. However i it was at 30 when i left and now i lost 2 so in theory it should be at 28? I added another person to my roster bumping it to "30" but after counting the heroes individually i have 31. Im really confused as to what's happened here. I dont see the two dead heroes in my roster so i think the game has added a hero to my roster... randomly.. somehow? Anyone experienced anything like this?

Sorry to answer a question with a question, but have you completed any of the 4 Darkest Dungeon quests yet? If so, then (unless things have changed), any surviving heroes from that quest no longer count against your barracks limits. They have little torches in their side panel icons to indicate they completed a Darkest quest. Therefore, if all 4 of them survive and defeat the Shuffling Horror for instance, then you could have a maximum of 34 heroes counting them; they will just no longer go on any of the remaining quests to the Darkest Dungeons (excluding the Courtyard and Farmstead I think). If you haven't won a Darkest quest yet, then I'm not sure.