If that is the case, you could use a system plugin designed specifically for that purposed named System -Tabulizer jQuery. By setting its parameter Remove Path(s) approprietly you can select which version of jQuery stays and which are removed or replaced.
For instance, the following value will remove jquery-latest.js, jquery.min.js loaded by the Jom Classifieds extension, and replace the jquery version 1.8 with the 1.7.2 version:
The full syntax is
In the above statement all paths will be replace with the zero string, with the exception of path3 that will be replaced by path4. All paths are separated by the semicolon (;), while each path can be either replaced by the empty string (e.g. path_from) or replaced by another string (e.g. path_from^path_to). So, path1 is equivalent to path1^, path2 is equivalent to path2^ and so on.
The "System - Tabulizer jQuery" plugin comes preinstalled and enabled with the Tabulizer revision 4.0.23 and onwards. You may disable it, if you don't have any jquery conflicts in your system or if you don't use the advanced Tabulizer features.
Even though is was developed primarily for the benefit of Tabulizer extension, it can be used for resolving jquery conflicts in general and in any Joomla system.