Why no parlay and can't lose parlay

This is a two part thread. 1-why won't the sportsbooks let me bet a same team baseball or hockey parlay of the total to the game result(not $ line)? They will let me bet a same team game to the total in basketball or football.and that is the second part of the thread. Assume the following basketball game, team A is playing team B. The line is
A -2 and the total is 220, both are -110. For now, forgetting a tie, there are only 4 outcomes. A wins over, A wins under, B wins over, B wins under. If you bet any two of the 4 possible outcomes, it would be a 50/50 bet, but I am getting $13 for a $10 bet. On the same game bet a $5 parlay on A to the under and bet a $5 parlay on B to the over. A $5 parlay pays $13. I have invested $10 and if win, I collect 13 on a 50/50 bet. In the long run, after many bets, you should win half and lose half. When you lose, you lost $10. When you win, you win $13. So, on a 50/50 coin toss, you win $13 or lose $10. That is my can't lose parlay. Yes, in the short term you can lose, but in the long term, it will end up as a 50/50 bet.

Quote: gamblehead

This is a two part thread. 1-why won't the sportsbooks let me bet a same team baseball or hockey parlay of the total to the game result(not $ line)? They will let me bet a same team game to the total in basketball or football.and that is the second part of the thread. Assume the following basketball game, team A is playing team B. The line is
A -2 and the total is 220, both are -110. For now, forgetting a tie, there are only 4 outcomes. A wins over, A wins under, B wins over, B wins under. If you bet any two of the 4 possible outcomes, it would be a 50/50 bet, but I am getting $13 for a $10 bet. On the same game bet a $5 parlay on A to the under and bet a $5 parlay on B to the over. A $5 parlay pays $13. I have invested $10 and if win, I collect 13 on a 50/50 bet. In the long run, after many bets, you should win half and lose half. When you lose, you lost $10. When you win, you win $13. So, on a 50/50 coin toss, you win $13 or lose $10. That is my can't lose parlay. Yes, in the short term you can lose, but in the long term, it will end up as a 50/50 bet.
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I don't know the reason why they don't let you bet "Money Line x Total" for Baseball and Hockey, but I think you are working it out wrong for the next part (see below).

You collect $18 (inc stake) if one of the bets wins, but you invested $10 in total, so you are getting the equivalent of 8 to 10 (not 13 to 10).

(edit: see strike-through): I agree with the next post by unJon .

I don’t know any books that will allow a same game parlay of run line with total in baseball or puck line and total in hockey. It’s too correlated.