You can actually get past the bomb count limit of the bomb bag. Simply dupe over bombs and then get a bomb drop. Follow the same process again and the bomb count will keep raising. By constantly duping over bombs and going over 99 bombs, the game no longer gives you the correct amount you have. For example, you have 95 bombs, instead of showing the number "100" after getting another bomb drop, it will show "90" (but in reality you actually have 100 bombs.)
It is likely that the game represents digits above the number "100" with the number "9." After going on a loop of duping and getting drops, when you reach bomb count of 255, the bomb count will revert back to 5 bombs.