Multiple <meta> Tags with the Same Name

Using multiple meta tags with the same name is valid HTML.

But we don't know how search engines and other readers will interpret them. Either two meta tags will be concatenated or one of them will be ignored/overwritten.

Example: The PHP-function get_meta_tags() will ignore multiple meta tags with an equal name.

To avoid possible problems I would recommend to use a single meta tag:

<meta name="copyright" content="Company A, Company B" />

If the page contains multiple meta tags of the same type, Google will aggregate the content values. For instance, they will interpret

<META NAME="ROBOTS" CONTENT="NOINDEX">
<META NAME="ROBOTS" CONTENT="NOFOLLOW">

The same way as:

<META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW">

More details here:http://googlewebmastercentral.blogspot.ro/2007/03/using-robots-meta-tag.html

I guess most other search engines would handle the meta tags in the same way.