Multiple tokens in the image field

Ultimately, yes you can have multiple tokens in the fields. The bigger question is, does it make sense for the individual meta tag, or would that muck things up? Image meta tags have special handling to extract the image URLs from the values, if it recognizes there being multiple items and the meta tag supports multiple value (like og:image) it will output multiple tags; if there are multiple items but the meta tag only supports one value then it will only output the first one. BTW meta tags that support multiple values will separate based upon comma, because that's what a token uses to separate multiple values.

Another thing to consider is to create multiple defaults at admin/config/search/metatags, one for each content type, thus avoiding the problem entirely.

You're very welcome :)