duplicate meta because of dynamic url-need help

[ankitneuro]

hi I am getting error of duplicate meta because of dynamic url like

/index.php?searchstring=Education

/index.php?searchstring=baby

/index.php?searchstring=mobile

/index.php?page=5&param1=valu1&param2=value

site is http://www.searchforoffer.net


at first tell me these all will have same meta tags or different and if same then how to solve duplicate content problem ?? is canonical tag there for the same probleam or in google webmaster tool in site config. menure URL parameter is there to solve the problem of 4th Url in the given list??
/////////and modreter I need to give link for explaning my question please do not deal it as a spam///