Can Child page override Masterpage - SF 5

Hi,
I need to add flash banners from the admin site. I am trying with a Module Builder. 
The site has around 250 pages. For almost 230 pages, the flash files are same. For the remaining pages, the banner files are page specific. Earlier this was done using a usercontrol. The flash banner user control is given in master page. 
I am thinking of creating a common module for banner images meant for pages having same flash files and separate modules for those pages with different banner files.
The only option I can find is to add the common module in the master page.

I don't know whether the child page can override the master page control. Is this possible?
PLease help.

Thanks.