Sending different versions to fixed percentages of the launch list
If you want to send different versions of the same campaign to your entire launch list in one go, rather than testing them on smaller groups, you can use the Automation Center A/B splitter node as described above and set the paths to 50% each (for example).
This will randomly split the versions between the launch list and launch them all together. You can then analyze the results afterwards.
Please be aware, that the A/B Splitter node creates individual campaigns which are independent from each other as opposed to the A/B version function which is used rather for comparison purposes. You will not be able to reach the different campaigns from the same UI screen.