ROI duplicate read z values

[HowcanoeWang]

>>> roi = idp.ROI(shpfile, name_field=0)
>>> roi.get_z_from_dsm(p4d.dsm)
# key break
>>> roi
{0: array([[3.05903027e+05, 3.92072184e+06, 1.02866016e+03],
           [3.05903280e+05, 3.92073184e+06, 1.02866016e+03],
           [3.05913278e+05, 3.92073159e+06, 1.02866016e+03],
           [3.05913025e+05, 3.92072159e+06, 1.02866016e+03],
           [3.05903027e+05, 3.92072184e+06, 1.02866016e+03]]),
9: array([[ 306213.63593707, 3919553.43964345],
          [ 306213.88877808, 3919563.43793896],
          [ 306223.8870733 , 3919563.18509768],
          [ 306223.63423231, 3919553.18680272],
          [ 306213.63593707, 3919553.43964345]])}

>>> roi_short = roi[0:10]
# read z again
>>> roi_short.get_z_from_dsm(p4d.dsm)
{0: array([[3.05903027e+05, 3.92072184e+06, 1.02866016e+03, 1.02866016e+03],
           [3.05903280e+05, 3.92073184e+06, 1.02866016e+03, 1.02866016e+03],
           [3.05913278e+05, 3.92073159e+06, 1.02866016e+03, 1.02866016e+03],
           [3.05913025e+05, 3.92072159e+06, 1.02866016e+03, 1.02866016e+03],
           [3.05903027e+05, 3.92072184e+06, 1.02866016e+03, 1.02866016e+03]]),
9: array([[3.05912519e+05, 3.92070159e+06, 1.03178625e+03],
           [3.05912772e+05, 3.92071159e+06, 1.03178625e+03],
           [3.05922771e+05, 3.92071134e+06, 1.03178625e+03],
           [3.05922518e+05, 3.92070134e+06, 1.03178625e+03],
           [3.05912519e+05, 3.92070159e+06, 1.03178625e+03]])