I think you might have a Russian example of a noble family's coat of arms. Look at the attached site for Russian coat of arms. There are a couple of double headed eagles with a crown on top. I didn't look at all of them very close.
With that type of back attachment, I'm thinking a uniform collar pin.
Since you didn't offer the dimensions and we don't know where it was found, that's just a guess.
Hapsburg. No doubt. Can you see the Golden Fleece hanging between the eagles feet? That's the giveaway. The Hapsburgs were Austrian but also a branch in Spain. Gary