I see, I didn't really grasp the double functionality. You can also add in a tabs script to the page to create that. I'm not sure how Wow Slider will mix with it, as I haven't used it, but it might be ok. It can get a bit messy to mix functionality together like this, so do plenty of testing as you go.
There are two ways I can think to do this. Probably the better one would be to have each client gallery on a separate page, and for the tabs basically to be a menu. That would be more reliable.
Otherwise, firstly put all the wow galleries on one page, each inside a div. Then get a tabs script that hides all but one of those divs at a time. That's how I'd approach it.