how will google treat yoursite.com/page?a=1 and yoursite.com/page?a=2 will it treat them different or same url. Or is there any solution i want google to treat same page but with different content. All though the meta tag will be same.
These are different URLs, so Google (and all other search engines that I'm aware of) will treat them as two different URLs. If you're showing the same content on those pages, Google will generally notice that they're identical and only show one of them in the search results. If they're not showing the same content, they'll generally be treated the same as any other independent pages on your site.
Make sure you take advantage of parameter handling in Google Webmaster tools. True, it is better to have friendly URLs by the way of a URL Rewriter, but until you're ready to deploy that (there are probably higher priority issues), it's good to make sure that Google knows what your parameters are and has them marked properly.
See my picture from Google Webmaster Tools pasted below.
For example, you might tell it to ignore a parameter that carries a session or user related value (look at Amazon URLs for an example -- non-essential items can be ignored by the spider).
Specify your canonical see http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html
<link rel="canonical" href="http://www.example.com/product.php?item=swedish-fish" />