Can I look up sideboard notes between games 1&2 and between games 2&3?

Ruling: Yes, you can look up sideboard notes between games.

Nuances:

• You can refer to notes made prior to the match between games (rule 416.5)
• You do not have to reveal these pre-match notes to opponents
• During games, you can only refer to notes taken during the current match, not notes from outside the current game