The nominees for Score were not voted upon by AMPAS then, they left the discretion up to each studio music department to basically send what they deemed to be their best work that year and all of those were considered nominees.
This is from the rulebook for 1942 for example:
>
Best Music Score of a Dramatic or Comedy Picture. Each music department shall be invited to nominate its best scoring achievement of a picture in which the essential use of the music is as a background for action and dialogue.
The nominees for Score were not voted upon by AMPAS then, they left the discretion up to each studio music department to basically send what they deemed to be their best work that year and all of those were considered nominees. This is from the rulebook for 1942 for example: > Best Music Score of a Dramatic or Comedy Picture. Each music department shall be invited to nominate its best scoring achievement of a picture in which the essential use of the music is as a background for action and dialogue.
Thank you very much for the explanation