I am receiving odds_change messages from the Live Odds producer before the handover message from pre-match, is this normal?

In most cases the odds_change from the live producers will be sent before the handover message. You can ignore pre-match odds changes as long as you deactivate the markets that pre-match offered, and is not offered by the live producer. However, it is best to handle the messages as they are supposed to be. Deactivate the markets which pre-match sends as deactivated, and ignore the markets that pre-match send with status "handed over".