Three guys are in the middle of doing back flips.
Three guys are in the middle of doing cartwheels.
Cartwheels and back flips are not the same thing.
exists p1 x1 x2.(n_middle(x2) & exists e1 s1 x3 x4.(in(x1,x2) & a_back(s1) & Manner(e1,s1) & Theme(e1,x4) & Actor(e1,x3) & v_do(e1) & n_flip(x4) & (x2 = x3)) & n_guy(x1) & card_eq_3(x1))
exists p1 x1 x2.(n_middle(x2) & exists e1 x3 x4.(in(x1,x2) & Theme(e1,x4) & Actor(e1,x3) & v_do(e1) & n_cartwheel(x4) & (x2 = x3)) & n_guy(x1) & card_eq_3(x1))