Risolved.
I configured two accounts in my SNAP plugin: Facebook and Twitter.
SNAP posts my article on Facebook and Twitter in “normal” format.
But Facebook and Twitter are connected by an application (Facebook to Twitter). On Facebook page I can read tweets in a tab and my Facebook application sends posts on Twitter account. So in my Twitter account I see a normal tweet by SNAP and a Twitter card by Facebook application, of the same post.
I risolved by disabling SNAP autopost on Twitter, so SNAP posts my article only into my Facebook page. Then Facebook application posts Twitter cards in my Twitter account.
Thank you so much.
