Izzo and Vallado algorithm are used for the Lambert Problem. Both yield different answers

izzo_vallado_compare.py

from poliastro.iod.vallado import lambert as lambert_v
from poliastro.iod.izzo import lambert as lambert_i 
from astropy import units as u, constants as c


if __name__ == "__main__":
    k = (c.GM_earth.to(u.km ** 3/ u.s ** 2))
    r0 = ([10000., 0, 0] * u.km)
    rf = ([8000., -5000, 0] * u.km)
    tof = 2*u.hour
    v_vallado = lambert_v(k, r0, rf, tof,short=True) #This is the correct answer 
    v_iz = lambert_i(k,r0,rf,tof,0)
    print(next(v_vallado))
    print(next(v_iz))