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አማርኛ A double multiplies two prices into one bet that needs both legs to land. It is the smallest accumulator and the clearest illustration of the family's economics: probability multiplies down while the bookmaker's margin stacks up.
Doubles have one honest use-case: two genuinely underpriced selections, where multiplying two positive edges compounds them. Two fairly-priced picks in a double are strictly worse than the same picks as singles.
Two legs at 2.10, each fairly a coin flip: the double pays 4.41 against a true 25% chance (fair 4.00) — wait, that is value only if the legs were priced ABOVE fair. At fair 2.00 legs, a 2.10 double leg carries edge; two of them compound to 4.41 vs fair 4.00. Margin-laden 1.90 legs compound the wrong way: 3.61 paid vs fair 4.00.