[SPOILERS] Pandemic Legacy Upgrades

** SPOILERS SPOILERS AND MORE**

So just finished January (yea I know it's early) and I had a question about upgrades. In the book it says you can "choose the same upgrade twice".

My question is can two different character share the same upgrade. Me and my girlfriend are playing Medic/Scientist. She chose the pilot and at the end of our second game in January (we won!) I was wondering if I could be a pilot too. Do I just write it in? Do we remove stickers? If we both want the same character upgrade does one get the sticker does the other just write?

I just wasn't sure how that works. Thanks for any help!