multiple lang encodings in a page

Hey there.

The first professional web site that I have created is a Turkish one. In many widely visited Turkish pages, I've noticed double encoding such as:

<meta http-equiv='Content-Type' content='text/html; charset=windows-1254'>
<META HTTP-EQUIV='Content-Type' CONTENT='text/html; charset=ISO-8859-9'>

The first encoding is the one for (in this case) Turkish Windows encoding, which works as well in Macs. The second one is something else which I don't know. Does giving multiple encodings direct the visitors' browser to the "first available encoding they have" on their computers? For example is this the case:

If you don't have Turkish characters/encoding installed in your computer, your browser automatically switches to the second encoding?

By the way I'm wondering what the language-special characters turn out when the site is viewed by a non-Turkish recipient. Though I'm not sure to ask this here, I'm wondering how you guys see the characters in the page (hope it's not appropriate). The address is http://www.prowide.com.tr and I should warn you that because of many pics it may load not instantaneously. I didn't want to use flash and the minimum acceptable quality in Photoshop led me to save all those pictures that way. Any suggestions along with technical directions/instructions are welcome (I know many things that are possible which I don't know how to use or edit).

Thanks a lot.

Ah I'd already forgot. The site's aim now is to reach Turkish people around the world, not only to those in Turkey. Soon I'll upload English pages when I get the translations. So I'll need double encodings anyway but I don't know if they confuse the browsers. Actually all the English characters are viewed without a problem in TR encoding however those don't have TR encoding are my concern.

What do u suggest?