|There used to be a few 'dual 56K' dialup modems which were essentially two 56K modems requiring two separate phone lines. They were designed to work together and had software to merge the two inputs. So download speed was doubled.|
If such a thing was possible with wireless and other network connections you'd have to have hardware and software specifically designed to do that--you couldn't just combine two different connections on your own and have it work.
I doubt anyone would bother trying to 'invent' such a thing. Faster single connections would be the way to go.