Two photographers cataloging an event.
Two photographers are taking pictures of a wedding.
Cataloging and taking pictures mean something different.  The event is not implied to be a wedding.
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_catalog(e1) & n_event(x3) & (x1 = x2) & n_photographer(x1) & card_eq_2(x1))
exists e1 x1 x2 x3.(of(e1,x3) & n_wedding(x3) & Theme(e1,x2) & Actor(e1,x1) & v_take(e1) & n_picture(x2) & n_photographer(x1) & card_eq_2(x1))