With a second Ultimate Vault Hunter pack on the way for Borderlands 2 next week (once again highlighting the pitfalls of "ultimate" in your title), Gearbox Software explains how the second level cap boost will work, noting that each Ultimate Vault Hunter pack boosts the cap by 11 levels, so both must be installed to raise the level cap from 50 all the way to 72. They have a chart outlining the benefits of owning one or both of the packs along with the following explanation:

As you can see, Ultimate Upgrade 2 Pack does more than just add 11 new levels for characters to grow into – it also includes a challenging new map (Raid on Digistruct Peak) for hardcore players!

Packed full of ultra-powerful enemies, Raid on Digistruct Peak is an unrelenting gauntlet for Pandora’s toughest to prove their mettle. Those that defeat the challenge at Level 72 will earn rewards unlike anything Borderlands 2 players have seen before – most notably, the ability to wield insane loot that exceeds the Level 72 cap (just imagine what a Level 80 Conference Call looks like) …and face even harder foes. For more details on that, hit up this article on Digital Trends.