ensemble notation

I'm copying Beethoven's Fidelio Overture into Notion 3, and in several places where there are two flutes, two horns, etc., "a2." appears above the staff. I'm guessing that it indicates that either both or one of the instruments plays that part, but I don't have a clue which. Can anyone enlighten me?

Thanks,

Norm

The marking "a2" is used to indicate that both players should play the part together, in unison. Here's the requisite Wikipedia article.

The marking "a2" is used to indicate that both players should play the part together, in unison. Here's the requisite Wikipedia article.

Thanks! Problem solved.