Vasari Corridor/Uffizi

Hi, Giangilberto from Milan, If I were you, I would rely solely on the official regulations found on the Uffizi Gallery's official website.
It clearly states there that holders of tickets including the Vasari Corridor supplement may enter the Gallery of Statues and Paintings two hours early to tour it before accessing the Vasari Corridor, indeed, re-entering the Uffizi is not possible once the corridor tour has begun.
The route is one-way only, proceeding from the Uffizi to Palazzo Pitti, not the other way around.

Gallery of Statues and Paintings with Vasari Corridor supplement: Full price €43.00 (if purchased on the same day as entry to the museum), Full price €47.00 (if purchased before the day of entry to the museum), reduced price €2.00, free;

5-day passepartout with Vasari Corridor supplement: Full price €58.00, free.

Furthermore, visitors holding the two aforementioned admission passes, by checking the mandatory box acknowledging these Regulations, declare that if they arrive late at the entrance to the Gallery of Statues and Paintings (specifically, with less than the 2 hours required for the standard Gallery visit), they are aware of the reduced time available to tour the Gallery of Statues and Paintings. They also acknowledge that they cannot re-enter the Gallery of Statues and Paintings after completing the tour of the Vasari Corridor, given that all Uffizi Galleries tickets are valid for a single entry unless otherwise specified. Please note that it takes a minimum of 45 minutes (estimated time) to travel from the entrance of the Gallery of Statues and Paintings to the meeting point for the Vasari Corridor (Room D19 on the Gallery’s first floor).

The regulations clearly state that even holders of the five-day pass cannot re-enter the Uffizi Gallery, that is precisely the interpretation of the Italian text. My advice is to email the Uffizi directly to confirm if this rule is indeed enforced, meaning that, for instance, you cannot re-enter the Uffizi after visiting the Vasari Corridor.
Alternatively, I can contact them myself to ask how this works.

https://www.uffizi.it/en/notices/rules-for-accessing-the-vasari-corridor

Thank you, @Giangilberto! I should have been more precise regarding the 5-day passport. My intention with purchasing that is to enter the Uffizi twice--two separate times, perhaps on a different day--one time to see the galleries and another time to bypass the galleries to visit the Corridor.

I agree with you that it is risky to count on being able to enter early which is why I wanted asked the question to discover if others have been able to.

Thank you for your help!

Is the 5-day passeport a solution that would allow us to enter the
Uffizi a second time in order to get to the Corridor?

According to the Uffizi's website, no. To access the corridor you must pay the higher ticket price....

"Passepartout 5 days with additional fee for the Vasari Corridor costs 58 €."

...and it counts as the single entry to the Uffizi that the Passepartout provides. Given the small numbers of people allowed through per time slot, being on time is important lest you lose your reserved slot, and I wouldn't count on being allowed into the galleries before your reserved time.

Even annual membership holders must pay an extra 20 € fee and make a reservation for the corridor, although that membership allows unlimited entry to the museums. So, you could do the museums + corridor on one day, and just the museums on another. What I'm unclear about is if an annual pass might allow you entry to the museums at any time on the same day you have a later-day reservation for the corridor, so you could go in the morning and end your visit via the corridor in the afternoon. You could ask if that's a possibility?

https://www.uffizi.it/en/contacts
https://www.uffizi.it/en/pages/annual-subscriptions

Otherwise, you'd need to purchase two entry tickets/reservations for two different days or times of same day: one that includes the corridor, and another for just the museums.