Well, I think it is perfectly fine if you use names which are easy to say together, or often come in a first name pair, like [name]Mary[/name] ___ ([name]Mary[/name] [name]Louise[/name] is nice), ___ [name]Jane[/name] ([name]Cara[/name] [name]Jane[/name]) or [name]Anna[/name] ____ ([name]Anna[/name] [name]Laurel[/name]). Also, two names which you would shorten to nicknames that flow well is good - [name]Elizabeth[/name] [name]Mabel[/name] becomes [name]Betty[/name] [name]Mae[/name], for example.
However, I think the names have to go together well in style and origin, must be very easy to say together, and have no possible confusion in the spelling. You could not use two unusual names, because [name]Arabella[/name] [name]Theodosia[/name] or the like would be an awful lot of name!
Also, be flexible with what you allow your child to be called. I have known a couple of people with long, hard double names - things like [name]Honora[/name] [name]Amelia[/name], which are a mouthful and blend together - who will not allow any shortening of this, whether it is using only one of the names, or any nickname, and this is so irritating. You can’t protest, because it is their name, but it is hard to say, and must be a great pain on forms et cetera.
You should also remember that, should you only give one name, you can always use the child’s middle, or put the names together to get a nn; my friend named her daughter [name]Penelope[/name] [name]Rose[/name], and she calls her [name]Posy[/name], for example.