do openuserjs checks the updateURL from time to time and updates stored version of a script?

OUJS doesn't do anything like that... however the .user.js engine does. e.g. Greasemonkey and others.

concrete example:

As you may have already figured out you posted two scripts with two different @names... when you changed the @name it will install a 2nd script as per .user.js engine specifications. We currently mirror that functionality with our URLs.

If this not happening automatically can i trigger it manually?

Assuming an end user has script updating enabled then bump your @version. Again this is all in the .user.js engines.