Different domains and duplicate content

Is it a problem?

[Dan0077]

Hi there

Ive been reading this forum for a while now but this is my first post. I kind of want something cleared up. I have read a few posts about duplicate content but i am still unsure whether it is actually a problem or not.

I have 2 domain names:
1. www.word1word2.co.uk
2. www.word1-word2.co.uk

If these contain exactly the same content will that cause a problem in G or can it tell they are both from the same owner?

I currently have another site with the same set up and it is lost in G. I do not want the same thing to happen again.

A lot of people have said a 301 redirect can fix this but my web host say they cant do it. If it will cause a problem is there another way to get round it or is it best to just lose one of the domains and keep one?

Thanks for the help
Dan