Gaming friendly a NO but...

Is it legal to equip Chewee Falcon's with a Chewee upgrade?

Quantum Space...

no

Can you explain why it is illegal to do?

it is a named /unique card. cant have the same "character" twice.

Any card with the bullet symbol in front of it's name is unique. No other card with that name may be in the list, even if it isn't the same card. So, you can't have R2-D2 the astromech droid and R2-D2 the crew member in the same list, nor can you have Chewbacca as crew of the ship Chewbacca is flying.

Thanks a lot.

What they said. However, if you are playing in teams (2 on 2 or 3 on 3 etc), it is legal, provided you EACH only have one unique character in your list. So, if you had a falcon with Chewie piloting, your teammate could have the same.

No it isn't. Or at least, it isn't legal in team epic tournaments. I can't actually find official rules for 200 point 2v2 dogfights, so I can't say if FFG has a stance on that. But the Epic tournament rules state that a team can't field two of the same unique- In faction-based mirror matches, you and your opponent can have the same unique card because FFG isn't going to make someone change their list, but you and your partner are able to plan out list building well in advance, so that isn't a concern.