Spence Condors - Advice

greetings all,
I have the opportunity to purchase a small collection of 18th century condors and was looking for any advice on determining authenticity. They are allegedly from an older collection and appear from the photos to be in quite nice shape.
Thanks!
Here are a few photos:

 

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I know nothing about these but they do all seem to have rotation errors.

 

Ha!

 

Something about them looks cleaned. The precise fields around the character on the first picture....