How to display the same node twice in one teaser?
There are a lot of ways you could accomplish that.

One way that seems to match your requirements is using the field collection module.

You could have a multiple value field collection field on your content type and that field collection could have your title, subtitle and image fields.

It depends somewhat on all your requirements though.

For example, this might work very well for your views (like the taxonomy one) if you want both blocks to show one after the other (since you have a view of nodes and these are both on the same node), but maybe it wouldn't be as good a solution if you wanted them spread out (in which case it might be better if they were 2 separate nodes).