Open Question: I want to twin two sleeping bags, how should I do it?

I have a Eureka Wild Basin 0 Degree bag that has a #5 two way right zip. I am looking for a sleeping bag that is compatible to twin with. Does it have to be from the same manufacturer? Or does it just have to be the same zipper? I would prefer to order from the internet, so trying it out before buying isn't really an option. Would like some information from somebody who has already paired sleeping bags before. Thanks.

Source:
http://answers.yahoo.com/question/index?qid=20110426141508AAgmqSH

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