No bug to exploit. It happened due to cross-matching and rounding. Someone got matched via cross matching which took a fraction of a penny of my back bet. When my bot cancelled the bet the rounding returned£2, although the real value would have been less. As I still had a part bet on the market when the selection won it returned a rounded £0.01.
I don’t think you could ever be in a position to exploit this as it’s always going to require a cross match that works partly using magic (or a method not fully disclosed by the exchange). Although saying that, you’d think they’d prevent this type of occurrence. Or do they let it happen to suggest there is no manipulation? The mind boggles. Good day.