As it stands now, multiple updates in the same transaction can have the same key, timestamp and transaction id combination meaning that they will clobber prior entries in the lookaside. This is fine for most updates since the latest is the only relevant one however this will cause data loss in the case of modifies.

There probably needs to be some logic in lookaside eviction where we detect multiple modifies for the same key and squash them into a standard update before lookaside evicting.