DIY Power Cable Advise Needed

Ok all you DIY junkies. I am trying to put together a power cable using double runs of 10AWG wire. The problem is that all of the connectors (Wattagate, Hubble, Marinco, etc) only accept one 10AWG wire. So how would you terminate two 10 AWG wires into one. So far the best way is to just solder them together and wrap with Teflon tape and heat shrink. There must be some better way. I am looking for advise from somebody who has done this kind of thing before. Is there a high quality connector that can be used to joing two 10AWG wires into one? (The wires are stranded - not solid). Any suggestions would be appreciated. I am trying to stay away from the run of the mill "butt" connectors. One of the local cable houses here says they would hit it with a 50 Ton press and form it using a "cold" welding technique if it were done there. This really doesn't help me though. Thanks - Dan.