Powerup Duration 2 is a custom name given to the unused upgrade, as official text for the name was never made.
Powerup Duration 22

Powerup Duration 2 is an unused upgrade which increases the duration of a powerup when used. It can be stacked with Powerup Duration 1 and is also identical to it. Interestingly enough, it can also increase the duration of Reveal Vase and Move Vase, allowing you to execute more actions within a single use of a powerup. It uses Mower Launch's texture as a placeholder.

Unlocked: Via hacking

Description: Increase the duration that your powerups are active.

Internal name: upgrade_powerup_duration_2