Here is a tip on how to load two shuttles continuously without first cutting the thread from the ball, and get an almost equal amount of thread in each shuttle. This works with Clover shuttles or its equivalent, and with thread size 20.
Load the first shuttle until full. Then continue by winding the thread over the outside of the shuttle like this -
The trick is to make 150 rounds over the shuttle, counting as you go. When you reach 150, cut off the thread from the ball and start loading the second shuttle with the cut end off the first shuttle. And you get this -
Two shuttles loaded with thread continuously. The term often used to refer to this is CTM - Continuous Thread Method.
If you plan to use beads, as I have here, string the beads before you start loading the first shuttle.