They made a mistake; they are human; humans make mistakes. Humans make more mistakes when they are tired. Paphos and back in a day is a long shift. Who knows what their rosters had them doing before? It will all be looked into. They work for a charter company, and at the end of the knackering summer season they are probably dulled by cumulative fatigue. The proposed Euro FTL changes will exacerbate the problem. What happened here just is the sort of mistake that usually diligent and professional people make when they are tired.
Some of the comments here are no doubt made by people who've never actually experienced an airline roster.