I have no clue why OpenGraph uses non-standard attributes on their meta tags, but if you are adding both OpenGraph information for Facebook and Twitter cards, any redundant field that you already have as OpenGraph Twitter will make use of: developer.twitter.com/en/docs/tweets/optimize-wit…
When using Open Graph protocol to describe data on a page, it is easy to generate a Twitter card without duplicating tags and data. When the Twitter card processor looks for tags on a page, it first checks for the Twitter-specific property, and if not present, falls back to the supported Open Graph property. This allows for both to be defined on the page independently, and minimizes the amount of duplicate markup required to describe content and experience.