We are drafting wrestlers, not weights. So if you draft Ashmore you will get Ashmores points, whether they are at 125 or 133.
The backup rule is intended mainly for guys who get injured. So lets say you drafted Brent Metcalf, and halfway through the season he suffered a career ending injury. Rather then saying "shit, you are out of luck" you get to score points for his backup. IE lets say Matt Balleweg moved down to 149 because of Metcalfs injury (this is just to give you an example not because its realistic). Then every Dual Iowa wrestled you would be able to score whatever points Balleweg scores by starting Metcalf.
Originally we had it so that you had to name the backup (IE start Balleweg in your lineup instead of Metcalf to score his points) but this created a lot of problems because it often wasn't clear when an injured guy would be wrestling, nor was it always certain who his backup would be.
Now lets go back to your Hypothetical example again. Lets say you drafted Ashmore, and someone else drafted Prado (I dont know why the F they would do that... but if They did). If ashmore is starting at 133 you get his points. But if Ashmore were to get injured, you would NOT be able to score Prados points as his backup, since Prado is on another team.
To give you an example of a real life scenario, if one guy drafts Leclere and thats it he gets points for the entire year at 141 during Iowa duals, no matter who wrestles. If he drafts Leclere and someone else drafts Slaton, the guy who drafted Leclere is out of Luck if slaton starts.