What's the point of making a small bet if you see that the odds have good value? Maybe only if you are fundamentally trying to show that you estimate possible outcomes more accurately than the bookmaker and the bet size itself is not important. In this case, a multiple bet on two outcomes will give 1.38 x 1.39 = 1.92, almost doubling the original amount. In my opinion, this is an attractive option for cash betting.
The problem is there is no good chance for the team given by the big odd to win the match so that placing bets in smaller amounts is much better. It was proven that Man United lost the match and even though I lost the bet but did not really affect because the bet I put in a small amount. I often do this kind of betting in football even though the opportunity to win is quite small but I like the challenges.
But if I can make predictions that are far more accurate and the possibility of the team can win the match then I will place a bet in a slightly larger amount and this applies only during certain matches that can convince me to make predictions.