I've come across
double third cousins, who are third cousins through two different routes as the same two families had two separate marriages between them that leads to this situation.
For DNA comparisons, I see from this table (found here: http://isogg.org/wiki/Autosomal_DNA_statistics#mediaviewer/File:Shared_cM_Project_v2_updated.png)
That third cousins would share an average of 79 cM and vary between 0–198 cM. In this case, I found 194.3 cM which seems to support the double third cousins situation, but wonder if we can be more specific as to what to expect for average and range in such a situation.
Would double 3rd cousins move one into needing triangulation or away from it to confirm the connection?
I would think it would move the relationship closer and thus be considered closer than 3rd cousins, but with DNA it might be more complicated than that.