Brain fart on free throw followed by tech

[UNIgiantslayers]

I'm not sure that we handled this correctly, but it was last night's wreck league so I was not too worried about it, just want to make sure I get it right in the future if I'm not officiating a game of former JV hacks.

A1 goes in for layup, B1 slides under him while A1 in air, basket good & blocking foul on B1. While getting ready to shoot the throw, B1 asks me what he did, and I told him he slid under the shooter to which he replies "that's f***ing bulls***." Tweet, whack. We cleared the lanes, and shot 2 for the original foul (both of which A1 made). That's when it hit me that we should have only shot one since the try was good. We got together and counted the second made shot on the second throw and gave them the opportunity to change shooters, which they did not, then shot the 3rd free throw, or what should have been the second of the T shots. My question is should this happen in the future, is there a better way to handle this other than not falling asleep on number of free throws for each foul?